Merge remote-tracking branch 'huoyaoyuan/master' into health-processor

# Conflicts:
#	osu.Game.Rulesets.Catch/CatchRuleset.cs
#	osu.Game.Rulesets.Mania/ManiaRuleset.cs
#	osu.Game.Rulesets.Taiko/TaikoRuleset.cs

.idea/.idea.osu.Desktop/.idea/runConfigurations/CatchRuleset__Tests_.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="CatchRuleset (Tests)" type="DotNetProject" factoryName=".NET Project" folderName="Ruleset">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Catch.Tests/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Catch.Tests.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Catch.Tests/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Catch.Tests.dll" />
     <option name="PROGRAM_PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Game.Rulesets.Catch.Tests" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.0" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <browser url="http://localhost:5000" />
     <method v="2">
       <option name="Build" enabled="true" />

.idea/.idea.osu.Desktop/.idea/runConfigurations/ManiaRuleset__Tests_.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="ManiaRuleset (Tests)" type="DotNetProject" factoryName=".NET Project" folderName="Ruleset">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Mania.Tests/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Mania.Tests.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Mania.Tests/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Mania.Tests.dll" />
     <option name="PROGRAM_PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Game.Rulesets.Mania.Tests" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.0" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <browser url="http://localhost:5000" />
     <method v="2">
       <option name="Build" enabled="true" />

.idea/.idea.osu.Desktop/.idea/runConfigurations/OsuRuleset__Tests_.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="OsuRuleset (Tests)" type="DotNetProject" factoryName=".NET Project" folderName="Ruleset">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Osu.Tests/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Osu.Tests.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Osu.Tests/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Osu.Tests.dll" />
     <option name="PROGRAM_PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Game.Rulesets.Osu.Tests" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.0" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <browser url="http://localhost:5000" />
     <method v="2">
       <option name="Build" enabled="true" />

.idea/.idea.osu.Desktop/.idea/runConfigurations/TaikoRuleset__Tests_.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="TaikoRuleset (Tests)" type="DotNetProject" factoryName=".NET Project" folderName="Ruleset">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Taiko.Tests/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Taiko.Tests.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Rulesets.Taiko.Tests/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Taiko.Tests.dll" />
     <option name="PROGRAM_PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Game.Rulesets.Taiko.Tests" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.0" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <browser url="http://localhost:5000" />
     <method v="2">
       <option name="Build" enabled="true" />

.idea/.idea.osu.Desktop/.idea/runConfigurations/Tournament.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="Tournament" type="DotNetProject" factoryName=".NET Project" folderName="Tournament">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Desktop/bin/Debug/netcoreapp3.0/osu!.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Desktop/bin/Debug/netcoreapp3.1/osu!.dll" />
     <option name="PROGRAM_PARAMETERS" value="--tournament" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Desktop" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.0" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <method v="2">
       <option name="Build" enabled="true" />
     </method>

.idea/.idea.osu.Desktop/.idea/runConfigurations/Tournament__Tests_.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="Tournament (Tests)" type="DotNetProject" factoryName=".NET Project" folderName="Tournament">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Tournament.Tests/bin/Debug/netcoreapp2.1/osu.Game.Tournament.Tests.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.1/osu.Game.Tournament.Tests.dll" />
     <option name="PROGRAM_PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Game.Tournament.Tests" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v2.1" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <browser url="http://localhost:5000" />
     <method v="2">
       <option name="Build" enabled="true" />

.idea/.idea.osu.Desktop/.idea/runConfigurations/osu_.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="osu!" type="DotNetProject" factoryName=".NET Project" folderName="osu!">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Desktop/bin/Debug/netcoreapp3.0/osu!.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Desktop/bin/Debug/netcoreapp3.1/osu!.dll" />
     <option name="PROGRAM_PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Desktop" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.0" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <method v="2">
       <option name="Build" enabled="true" />
     </method>

.idea/.idea.osu.Desktop/.idea/runConfigurations/osu___Tests_.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="osu! (Tests)" type="DotNetProject" factoryName=".NET Project" folderName="osu!">
-    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Tests/bin/Debug/netcoreapp3.0/osu.Game.Tests.dll" />
+    <option name="EXE_PATH" value="$PROJECT_DIR$/osu.Game.Tests/bin/Debug/netcoreapp3.1/osu.Game.Tests.dll" />
     <option name="PROGRAM_PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="$PROJECT_DIR$/osu.Game.Tests" />
     <option name="PASS_PARENT_ENVS" value="1" />
@@ -12,7 +12,7 @@
     <option name="PROJECT_ARGUMENTS_TRACKING" value="1" />
     <option name="PROJECT_WORKING_DIRECTORY_TRACKING" value="1" />
     <option name="PROJECT_KIND" value="DotNetCore" />
-    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.0" />
+    <option name="PROJECT_TFM" value=".NETCoreApp,Version=v3.1" />
     <method v="2">
       <option name="Build" enabled="true" />
     </method>

.vscode/launch.json

@@ -6,13 +6,13 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.0/osu!.dll"
+                "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.1/osu!.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build osu! (Debug)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"
@@ -23,13 +23,13 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.0/osu!.dll"
+                "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.1/osu!.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build osu! (Release)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"
@@ -40,13 +40,13 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Game.Tests/bin/Debug/netcoreapp3.0/osu.Game.Tests.dll"
+                "${workspaceRoot}/osu.Game.Tests/bin/Debug/netcoreapp3.1/osu.Game.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build tests (Debug)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tests/bin/Debug/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tests/bin/Debug/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"
@@ -56,13 +56,13 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Game.Tests/bin/Release/netcoreapp3.0/osu.Game.Tests.dll"
+                "${workspaceRoot}/osu.Game.Tests/bin/Release/netcoreapp3.1/osu.Game.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build tests (Release)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tests/bin/Release/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tests/bin/Release/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"
@@ -73,14 +73,14 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.0/osu!.dll",
+                "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.1/osu!.dll",
                 "--tournament"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build osu! (Debug)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Debug/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"
@@ -91,14 +91,14 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.0/osu!.dll",
+                "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.1/osu!.dll",
                 "--tournament"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build osu! (Release)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Desktop/bin/Release/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"
@@ -109,14 +109,14 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.0/osu.Game.Tournament.Tests.dll",
+                "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.1/osu.Game.Tournament.Tests.dll",
                 "--tournament"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build tournament tests (Debug)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"
@@ -127,14 +127,14 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.0/osu.Game.Tournament.Tests.dll",
+                "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.1/osu.Game.Tournament.Tests.dll",
                 "--tournament"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build tournament tests (Release)",
             "linux": {
                 "env": {
-                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.0:${env:LD_LIBRARY_PATH}"
+                    "LD_LIBRARY_PATH": "${workspaceRoot}/osu.Game.Tournament.Tests/bin/Debug/netcoreapp3.1:${env:LD_LIBRARY_PATH}"
                 }
             },
             "console": "internalConsole"

.vscode/tasks.json

@@ -95,7 +95,7 @@
             "problemMatcher": "$msCompile"
         },
         {
-            "label": "Restore (netcoreapp3.0)",
+            "label": "Restore (netcoreapp3.1)",
             "type": "shell",
             "command": "dotnet",
             "args": [

README.md

@@ -21,9 +21,9 @@ Detailed changelogs are published on the [official osu! site](https://osu.ppy.sh
 
 ## Requirements
 
-- A desktop platform with the [.NET Core SDK 3.0](https://www.microsoft.com/net/learn/get-started) or higher installed.
+- A desktop platform with the [.NET Core 3.1 SDK](https://dotnet.microsoft.com/download) or higher installed.
 - When running on Linux, please have a system-wide FFmpeg installation available to support video decoding.
-- When running on Windows 7 or 8.1, **[additional prerequisites](https://docs.microsoft.com/en-us/dotnet/core/install/dependencies?tabs=netcore30&pivots=os-windows)** may be required to correctly run .NET Core applications if your operating system is not up-to-date with the latest service packs.
+- When running on Windows 7 or 8.1, **[additional prerequisites](https://docs.microsoft.com/en-us/dotnet/core/install/dependencies?tabs=netcore31&pivots=os-windows)** may be required to correctly run .NET Core applications if your operating system is not up-to-date with the latest service packs.
 - When developing with mobile, [Xamarin](https://docs.microsoft.com/en-us/xamarin/) is required, which is shipped together with Visual Studio or [Visual Studio for Mac](https://visualstudio.microsoft.com/vs/mac/).
 - When working with the codebase, we recommend using an IDE with intelligent code completion and syntax highlighting, such as [Visual Studio 2019+](https://visualstudio.microsoft.com/vs/), [JetBrains Rider](https://www.jetbrains.com/rider/) or [Visual Studio Code](https://code.visualstudio.com/).
 
@@ -35,7 +35,7 @@ If you are not interested in developing the game, you can still consume our [bin
 
 **Latest build:**
 
-| [Windows (x64)](https://github.com/ppy/osu/releases/latest/download/install.exe)  | [macOS 10.12+](https://github.com/ppy/osu/releases/latest/download/osu.app.zip) | [iOS(iOS 10+)](https://testflight.apple.com/join/2tLcjWlF) | [Android (5+)](https://github.com/ppy/osu/releases/latest/download/sh.ppy.osulazer.apk)
+| [Windows (x64)](https://github.com/ppy/osu/releases/latest/download/install.exe)  | [macOS 10.12+](https://github.com/ppy/osu/releases/latest/download/osu.app.zip) | [iOS(iOS 10+)](https://osu.ppy.sh/home/testflight) | [Android (5+)](https://github.com/ppy/osu/releases/latest/download/sh.ppy.osulazer.apk)
 | ------------- | ------------- | ------------- | ------------- |
 
 - **Linux** users are recommended to self-compile until we have official deployment in place.

osu.Android.props

@@ -54,6 +54,6 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="ppy.osu.Game.Resources" Version="2019.1215.0" />
-    <PackageReference Include="ppy.osu.Framework.Android" Version="2019.1215.0" />
+    <PackageReference Include="ppy.osu.Framework.Android" Version="2019.1225.0" />
   </ItemGroup>
 </Project>

osu.Desktop/DiscordRichPresence.cs

@@ -1,6 +1,8 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
+using System.Text;
 using DiscordRPC;
 using DiscordRPC.Message;
 using osu.Framework.Allocation;
@@ -43,6 +45,10 @@ namespace osu.Desktop
             };
 
             client.OnReady += onReady;
+
+            // safety measure for now, until we performance test / improve backoff for failed connections.
+            client.OnConnectionFailed += (_, __) => client.Deinitialize();
+
             client.OnError += (_, e) => Logger.Log($"An error occurred with Discord RPC Client: {e.Code} {e.Message}", LoggingTarget.Network);
 
             (user = provider.LocalUser.GetBoundCopy()).BindValueChanged(u =>
@@ -77,8 +83,8 @@ namespace osu.Desktop
 
             if (status.Value is UserStatusOnline && activity.Value != null)
             {
-                presence.State = activity.Value.Status;
+                presence.State = truncate(activity.Value.Status);
-                presence.Details = getDetails(activity.Value);
+                presence.Details = truncate(getDetails(activity.Value));
             }
             else
             {
@@ -96,6 +102,27 @@ namespace osu.Desktop
             client.SetPresence(presence);
         }
 
+        private static readonly int ellipsis_length = Encoding.UTF8.GetByteCount(new[] { '…' });
+
+        private string truncate(string str)
+        {
+            if (Encoding.UTF8.GetByteCount(str) <= 128)
+                return str;
+
+            ReadOnlyMemory<char> strMem = str.AsMemory();
+
+            do
+            {
+                strMem = strMem[..^1];
+            } while (Encoding.UTF8.GetByteCount(strMem.Span) + ellipsis_length > 128);
+
+            return string.Create(strMem.Length + 1, strMem, (span, mem) =>
+            {
+                mem.Span.CopyTo(span);
+                span[^1] = '…';
+            });
+        }
+
         private string getDetails(UserActivity activity)
         {
             switch (activity)

osu.Desktop/osu.Desktop.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup Label="Project">
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
     <OutputType>WinExe</OutputType>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <Description>click the circles. to the beat.</Description>

osu.Game.Rulesets.Catch.Tests.iOS/Application.cs

@@ -5,7 +5,7 @@ using UIKit;
 
 namespace osu.Game.Rulesets.Catch.Tests.iOS
 {
-    public class Application
+    public static class Application
     {
         public static void Main(string[] args)
         {

osu.Game.Rulesets.Catch.Tests/.vscode/launch.json

@@ -7,7 +7,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Catch.Tests.dll"
+                "${workspaceRoot}/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Catch.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Debug)",
@@ -20,7 +20,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Release/netcoreapp3.0/osu.Game.Rulesets.Catch.Tests.dll"
+                "${workspaceRoot}/bin/Release/netcoreapp3.1/osu.Game.Rulesets.Catch.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Release)",

osu.Game.Rulesets.Catch.Tests/osu.Game.Rulesets.Catch.Tests.csproj

@@ -9,7 +9,7 @@
   </ItemGroup>
   <PropertyGroup Label="Project">
     <OutputType>WinExe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\osu.Game.Rulesets.Catch\osu.Game.Rulesets.Catch.csproj" />

osu.Game.Rulesets.Catch/Beatmaps/CatchBeatmapConverter.cs

@@ -4,7 +4,7 @@
 using osu.Game.Beatmaps;
 using osu.Game.Rulesets.Catch.Objects;
 using System.Collections.Generic;
-using System;
+using System.Linq;
 using osu.Game.Rulesets.Catch.UI;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Objects;
@@ -14,12 +14,12 @@ namespace osu.Game.Rulesets.Catch.Beatmaps
 {
     public class CatchBeatmapConverter : BeatmapConverter<CatchHitObject>
     {
-        public CatchBeatmapConverter(IBeatmap beatmap)
+        public CatchBeatmapConverter(IBeatmap beatmap, Ruleset ruleset)
-            : base(beatmap)
+            : base(beatmap, ruleset)
         {
         }
 
-        protected override IEnumerable<Type> ValidConversionTypes { get; } = new[] { typeof(IHasXPosition) };
+        public override bool CanConvert() => Beatmap.HitObjects.All(h => h is IHasXPosition);
 
         protected override IEnumerable<CatchHitObject> ConvertHitObject(HitObject obj, IBeatmap beatmap)
         {

osu.Game.Rulesets.Catch/CatchRuleset.cs

@@ -24,7 +24,7 @@ using System;
 
 namespace osu.Game.Rulesets.Catch
 {
-    public class CatchRuleset : Ruleset
+    public class CatchRuleset : Ruleset, ILegacyRuleset
     {
         public override DrawableRuleset CreateDrawableRulesetWith(IBeatmap beatmap, IReadOnlyList<Mod> mods = null) => new DrawableCatchRuleset(this, beatmap, mods);
 
@@ -32,7 +32,8 @@ namespace osu.Game.Rulesets.Catch
 
         public override HealthProcessor CreateHealthProcessor(IBeatmap beatmap) => new CatchHealthProcessor(beatmap);
 
-        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new CatchBeatmapConverter(beatmap);
+        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new CatchBeatmapConverter(beatmap, this);
+
         public override IBeatmapProcessor CreateBeatmapProcessor(IBeatmap beatmap) => new CatchBeatmapProcessor(beatmap);
 
         public const string SHORT_NAME = "fruits";
@@ -108,6 +109,12 @@ namespace osu.Game.Rulesets.Catch
                         new CatchModFlashlight(),
                     };
 
+                case ModType.Conversion:
+                    return new Mod[]
+                    {
+                        new CatchModDifficultyAdjust(),
+                    };
+
                 case ModType.Automation:
                     return new Mod[]
                     {
@@ -136,7 +143,7 @@ namespace osu.Game.Rulesets.Catch
 
         public override PerformanceCalculator CreatePerformanceCalculator(WorkingBeatmap beatmap, ScoreInfo score) => new CatchPerformanceCalculator(this, beatmap, score);
 
-        public override int? LegacyID => 2;
+        public int LegacyID => 2;
 
         public override IConvertibleReplayFrame CreateConvertibleReplayFrame() => new CatchReplayFrame();
     }

osu.Game.Rulesets.Catch/Mods/CatchModDifficultyAdjust.cs

@@ -0,0 +1,49 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Bindables;
+using osu.Game.Beatmaps;
+using osu.Game.Configuration;
+using osu.Game.Rulesets.Mods;
+
+namespace osu.Game.Rulesets.Catch.Mods
+{
+    public class CatchModDifficultyAdjust : ModDifficultyAdjust
+    {
+        [SettingSource("Fruit Size", "Override a beatmap's set CS.")]
+        public BindableNumber<float> CircleSize { get; } = new BindableFloat
+        {
+            Precision = 0.1f,
+            MinValue = 1,
+            MaxValue = 10,
+            Default = 5,
+            Value = 5,
+        };
+
+        [SettingSource("Approach Rate", "Override a beatmap's set AR.")]
+        public BindableNumber<float> ApproachRate { get; } = new BindableFloat
+        {
+            Precision = 0.1f,
+            MinValue = 1,
+            MaxValue = 10,
+            Default = 5,
+            Value = 5,
+        };
+
+        protected override void TransferSettings(BeatmapDifficulty difficulty)
+        {
+            base.TransferSettings(difficulty);
+
+            CircleSize.Value = CircleSize.Default = difficulty.CircleSize;
+            ApproachRate.Value = ApproachRate.Default = difficulty.ApproachRate;
+        }
+
+        protected override void ApplySettings(BeatmapDifficulty difficulty)
+        {
+            base.ApplySettings(difficulty);
+
+            difficulty.CircleSize = CircleSize.Value;
+            difficulty.ApproachRate = ApproachRate.Value;
+        }
+    }
+}

osu.Game.Rulesets.Mania.Tests.iOS/Application.cs

@@ -5,7 +5,7 @@ using UIKit;
 
 namespace osu.Game.Rulesets.Mania.Tests.iOS
 {
-    public class Application
+    public static class Application
     {
         public static void Main(string[] args)
         {

osu.Game.Rulesets.Mania.Tests/.vscode/launch.json

@@ -7,7 +7,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Mania.Tests.dll"
+                "${workspaceRoot}/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Mania.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Debug)",
@@ -20,7 +20,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Release/netcoreapp3.0/osu.Game.Rulesets.Mania.Tests.dll"
+                "${workspaceRoot}/bin/Release/netcoreapp3.1/osu.Game.Rulesets.Mania.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Release)",

osu.Game.Rulesets.Mania.Tests/osu.Game.Rulesets.Mania.Tests.csproj

@@ -9,7 +9,7 @@
   </ItemGroup>
   <PropertyGroup Label="Project">
     <OutputType>WinExe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\osu.Game.Rulesets.Mania\osu.Game.Rulesets.Mania.csproj" />

osu.Game.Rulesets.Mania/Beatmaps/ManiaBeatmapConverter.cs

@@ -24,8 +24,6 @@ namespace osu.Game.Rulesets.Mania.Beatmaps
         /// </summary>
         private const int max_notes_for_density = 7;
 
-        protected override IEnumerable<Type> ValidConversionTypes { get; } = new[] { typeof(IHasXPosition) };
-
         public int TargetColumns;
         public bool Dual;
         public readonly bool IsForCurrentRuleset;
@@ -37,10 +35,10 @@ namespace osu.Game.Rulesets.Mania.Beatmaps
 
         private ManiaBeatmap beatmap;
 
-        public ManiaBeatmapConverter(IBeatmap beatmap)
+        public ManiaBeatmapConverter(IBeatmap beatmap, Ruleset ruleset)
-            : base(beatmap)
+            : base(beatmap, ruleset)
         {
-            IsForCurrentRuleset = beatmap.BeatmapInfo.Ruleset.Equals(new ManiaRuleset().RulesetInfo);
+            IsForCurrentRuleset = beatmap.BeatmapInfo.Ruleset.Equals(ruleset.RulesetInfo);
 
             var roundedCircleSize = Math.Round(beatmap.BeatmapInfo.BaseDifficulty.CircleSize);
             var roundedOverallDifficulty = Math.Round(beatmap.BeatmapInfo.BaseDifficulty.OverallDifficulty);
@@ -69,6 +67,8 @@ namespace osu.Game.Rulesets.Mania.Beatmaps
             }
         }
 
+        public override bool CanConvert() => Beatmap.HitObjects.All(h => h is IHasXPosition || h is ManiaHitObject);
+
         protected override Beatmap<ManiaHitObject> ConvertBeatmap(IBeatmap original)
         {
             BeatmapDifficulty difficulty = original.BeatmapInfo.BaseDifficulty;

osu.Game.Rulesets.Mania/ManiaRuleset.cs

@@ -31,7 +31,7 @@ using osu.Game.Scoring;
 
 namespace osu.Game.Rulesets.Mania
 {
-    public class ManiaRuleset : Ruleset
+    public class ManiaRuleset : Ruleset, ILegacyRuleset
     {
         public override DrawableRuleset CreateDrawableRulesetWith(IBeatmap beatmap, IReadOnlyList<Mod> mods = null) => new DrawableManiaRuleset(this, beatmap, mods);
 
@@ -39,7 +39,8 @@ namespace osu.Game.Rulesets.Mania
 
         public override HealthProcessor CreateHealthProcessor(IBeatmap beatmap) => new ManiaHealthProcessor(beatmap);
 
-        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new ManiaBeatmapConverter(beatmap);
+        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new ManiaBeatmapConverter(beatmap, this);
+
 
         public override PerformanceCalculator CreatePerformanceCalculator(WorkingBeatmap beatmap, ScoreInfo score) => new ManiaPerformanceCalculator(this, beatmap, score);
 
@@ -153,6 +154,7 @@ namespace osu.Game.Rulesets.Mania
                         new ManiaModRandom(),
                         new ManiaModDualStages(),
                         new ManiaModMirror(),
+                        new ManiaModDifficultyAdjust(),
                     };
 
                 case ModType.Automation:
@@ -180,7 +182,7 @@ namespace osu.Game.Rulesets.Mania
 
         public override DifficultyCalculator CreateDifficultyCalculator(WorkingBeatmap beatmap) => new ManiaDifficultyCalculator(this, beatmap);
 
-        public override int? LegacyID => 3;
+        public int LegacyID => 3;
 
         public override IConvertibleReplayFrame CreateConvertibleReplayFrame() => new ManiaReplayFrame();
 

osu.Game.Rulesets.Mania/Mods/ManiaModDifficultyAdjust.cs

@@ -0,0 +1,11 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Game.Rulesets.Mods;
+
+namespace osu.Game.Rulesets.Mania.Mods
+{
+    public class ManiaModDifficultyAdjust : ModDifficultyAdjust
+    {
+    }
+}

osu.Game.Rulesets.Mania/Replays/ManiaReplayFrame.cs

@@ -27,7 +27,7 @@ namespace osu.Game.Rulesets.Mania.Replays
         public void ConvertFrom(LegacyReplayFrame legacyFrame, IBeatmap beatmap, ReplayFrame lastFrame = null)
         {
             // We don't need to fully convert, just create the converter
-            var converter = new ManiaBeatmapConverter(beatmap);
+            var converter = new ManiaBeatmapConverter(beatmap, new ManiaRuleset());
 
             // NB: Via co-op mod, osu-stable can have two stages with floor(col/2) and ceil(col/2) columns. This will need special handling
             // elsewhere in the game if we do choose to support the old co-op mod anyway. For now, assume that there is only one stage.

osu.Game.Rulesets.Osu.Tests.iOS/Application.cs

@@ -5,7 +5,7 @@ using UIKit;
 
 namespace osu.Game.Rulesets.Osu.Tests.iOS
 {
-    public class Application
+    public static class Application
     {
         public static void Main(string[] args)
         {

osu.Game.Rulesets.Osu.Tests/.vscode/launch.json

@@ -7,7 +7,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Osu.Tests.dll"
+                "${workspaceRoot}/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Osu.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Debug)",
@@ -20,7 +20,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Release/netcoreapp3.0/osu.Game.Rulesets.Osu.Tests.dll"
+                "${workspaceRoot}/bin/Release/netcoreapp3.1/osu.Game.Rulesets.Osu.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Release)",

osu.Game.Rulesets.Osu.Tests/TestSceneLegacyBeatmapSkin.cs

@@ -0,0 +1,155 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Audio;
+using osu.Framework.Graphics;
+using osu.Framework.IO.Stores;
+using osu.Framework.Testing;
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets.Osu.Objects;
+using osu.Game.Screens;
+using osu.Game.Screens.Play;
+using osu.Game.Skinning;
+using osu.Game.Tests.Visual;
+using osuTK;
+using osuTK.Graphics;
+
+namespace osu.Game.Rulesets.Osu.Tests
+{
+    public class TestSceneLegacyBeatmapSkin : OsuTestScene
+    {
+        [Resolved]
+        private AudioManager audio { get; set; }
+
+        [TestCase(true)]
+        [TestCase(false)]
+        public void TestBeatmapComboColours(bool customSkinColoursPresent)
+        {
+            ExposedPlayer player = null;
+
+            AddStep("load coloured beatmap", () => player = loadBeatmap(customSkinColoursPresent, true));
+            AddUntilStep("wait for player", () => player.IsLoaded);
+
+            AddAssert("is beatmap skin colours", () => player.UsableComboColours.SequenceEqual(TestBeatmapSkin.Colours));
+        }
+
+        [Test]
+        public void TestBeatmapNoComboColours()
+        {
+            ExposedPlayer player = null;
+
+            AddStep("load no-colour beatmap", () => player = loadBeatmap(false, false));
+            AddUntilStep("wait for player", () => player.IsLoaded);
+
+            AddAssert("is default user skin colours", () => player.UsableComboColours.SequenceEqual(SkinConfiguration.DefaultComboColours));
+        }
+
+        [Test]
+        public void TestBeatmapNoComboColoursSkinOverride()
+        {
+            ExposedPlayer player = null;
+
+            AddStep("load custom-skin colour", () => player = loadBeatmap(true, false));
+            AddUntilStep("wait for player", () => player.IsLoaded);
+
+            AddAssert("is custom user skin colours", () => player.UsableComboColours.SequenceEqual(TestSkin.Colours));
+        }
+
+        private ExposedPlayer loadBeatmap(bool userHasCustomColours, bool beatmapHasColours)
+        {
+            ExposedPlayer player;
+
+            Beatmap.Value = new CustomSkinWorkingBeatmap(audio, beatmapHasColours);
+            Child = new OsuScreenStack(player = new ExposedPlayer(userHasCustomColours)) { RelativeSizeAxes = Axes.Both };
+
+            return player;
+        }
+
+        private class ExposedPlayer : Player
+        {
+            private readonly bool userHasCustomColours;
+
+            public ExposedPlayer(bool userHasCustomColours)
+                : base(false, false)
+            {
+                this.userHasCustomColours = userHasCustomColours;
+            }
+
+            protected override IReadOnlyDependencyContainer CreateChildDependencies(IReadOnlyDependencyContainer parent)
+            {
+                var dependencies = new DependencyContainer(base.CreateChildDependencies(parent));
+                dependencies.CacheAs<ISkinSource>(new TestSkin(userHasCustomColours));
+                return dependencies;
+            }
+
+            public IReadOnlyList<Color4> UsableComboColours =>
+                GameplayClockContainer.ChildrenOfType<BeatmapSkinProvidingContainer>()
+                                      .First()
+                                      .GetConfig<GlobalSkinConfiguration, IReadOnlyList<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value;
+        }
+
+        private class CustomSkinWorkingBeatmap : ClockBackedTestWorkingBeatmap
+        {
+            private readonly bool hasColours;
+
+            public CustomSkinWorkingBeatmap(AudioManager audio, bool hasColours)
+                : base(new Beatmap
+                {
+                    BeatmapInfo =
+                    {
+                        BeatmapSet = new BeatmapSetInfo(),
+                        Ruleset = new OsuRuleset().RulesetInfo,
+                    },
+                    HitObjects = { new HitCircle { Position = new Vector2(256, 192) } }
+                }, null, null, audio)
+            {
+                this.hasColours = hasColours;
+            }
+
+            protected override ISkin GetSkin() => new TestBeatmapSkin(BeatmapInfo, hasColours);
+        }
+
+        private class TestBeatmapSkin : LegacyBeatmapSkin
+        {
+            public static Color4[] Colours { get; } =
+            {
+                new Color4(50, 100, 150, 255),
+                new Color4(40, 80, 120, 255),
+            };
+
+            public TestBeatmapSkin(BeatmapInfo beatmap, bool hasColours)
+                : base(beatmap, new ResourceStore<byte[]>(), null)
+            {
+                if (hasColours)
+                    Configuration.AddComboColours(Colours);
+            }
+        }
+
+        private class TestSkin : LegacySkin, ISkinSource
+        {
+            public static Color4[] Colours { get; } =
+            {
+                new Color4(150, 100, 50, 255),
+                new Color4(20, 20, 20, 255),
+            };
+
+            public TestSkin(bool hasCustomColours)
+                : base(new SkinInfo(), null, null, string.Empty)
+            {
+                if (hasCustomColours)
+                    Configuration.AddComboColours(Colours);
+            }
+
+            public event Action SourceChanged
+            {
+                add { }
+                remove { }
+            }
+        }
+    }
+}

osu.Game.Rulesets.Osu.Tests/TestSceneSpinnerRotation.cs

@@ -102,7 +102,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                     EndTime = 6000,
                 },
                 // placeholder object to avoid hitting the results screen
-                new HitObject
+                new HitCircle
                 {
                     StartTime = 99999,
                 }

osu.Game.Rulesets.Osu.Tests/osu.Game.Rulesets.Osu.Tests.csproj

@@ -9,7 +9,7 @@
   </ItemGroup>
   <PropertyGroup Label="Project">
     <OutputType>WinExe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\osu.Game.Rulesets.Osu\osu.Game.Rulesets.Osu.csproj" />

osu.Game.Rulesets.Osu/Beatmaps/OsuBeatmapConverter.cs

@@ -7,7 +7,7 @@ using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Osu.Objects;
 using System.Collections.Generic;
 using osu.Game.Rulesets.Objects.Types;
-using System;
+using System.Linq;
 using osu.Game.Rulesets.Osu.UI;
 using osu.Framework.Extensions.IEnumerableExtensions;
 
@@ -15,12 +15,12 @@ namespace osu.Game.Rulesets.Osu.Beatmaps
 {
     public class OsuBeatmapConverter : BeatmapConverter<OsuHitObject>
     {
-        public OsuBeatmapConverter(IBeatmap beatmap)
+        public OsuBeatmapConverter(IBeatmap beatmap, Ruleset ruleset)
-            : base(beatmap)
+            : base(beatmap, ruleset)
         {
         }
 
-        protected override IEnumerable<Type> ValidConversionTypes { get; } = new[] { typeof(IHasPosition) };
+        public override bool CanConvert() => Beatmap.HitObjects.All(h => h is IHasPosition);
 
         protected override IEnumerable<OsuHitObject> ConvertHitObject(HitObject original, IBeatmap beatmap)
         {

osu.Game.Rulesets.Osu/Mods/OsuModDifficultyAdjust.cs

@@ -0,0 +1,49 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Bindables;
+using osu.Game.Beatmaps;
+using osu.Game.Configuration;
+using osu.Game.Rulesets.Mods;
+
+namespace osu.Game.Rulesets.Osu.Mods
+{
+    public class OsuModDifficultyAdjust : ModDifficultyAdjust
+    {
+        [SettingSource("Circle Size", "Override a beatmap's set CS.")]
+        public BindableNumber<float> CircleSize { get; } = new BindableFloat
+        {
+            Precision = 0.1f,
+            MinValue = 1,
+            MaxValue = 10,
+            Default = 5,
+            Value = 5,
+        };
+
+        [SettingSource("Approach Rate", "Override a beatmap's set AR.")]
+        public BindableNumber<float> ApproachRate { get; } = new BindableFloat
+        {
+            Precision = 0.1f,
+            MinValue = 1,
+            MaxValue = 10,
+            Default = 5,
+            Value = 5,
+        };
+
+        protected override void TransferSettings(BeatmapDifficulty difficulty)
+        {
+            base.TransferSettings(difficulty);
+
+            CircleSize.Value = CircleSize.Default = difficulty.CircleSize;
+            ApproachRate.Value = ApproachRate.Default = difficulty.ApproachRate;
+        }
+
+        protected override void ApplySettings(BeatmapDifficulty difficulty)
+        {
+            base.ApplySettings(difficulty);
+
+            difficulty.CircleSize = CircleSize.Value;
+            difficulty.ApproachRate = ApproachRate.Value;
+        }
+    }
+}

osu.Game.Rulesets.Osu/OsuRuleset.cs

@@ -32,13 +32,13 @@ using System;
 
 namespace osu.Game.Rulesets.Osu
 {
-    public class OsuRuleset : Ruleset
+    public class OsuRuleset : Ruleset, ILegacyRuleset
     {
         public override DrawableRuleset CreateDrawableRulesetWith(IBeatmap beatmap, IReadOnlyList<Mod> mods = null) => new DrawableOsuRuleset(this, beatmap, mods);
 
         public override ScoreProcessor CreateScoreProcessor(IBeatmap beatmap) => new OsuScoreProcessor(beatmap);
 
-        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new OsuBeatmapConverter(beatmap);
+        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new OsuBeatmapConverter(beatmap, this);
 
         public override IBeatmapProcessor CreateBeatmapProcessor(IBeatmap beatmap) => new OsuBeatmapProcessor(beatmap);
 
@@ -130,6 +130,7 @@ namespace osu.Game.Rulesets.Osu
                     return new Mod[]
                     {
                         new OsuModTarget(),
+                        new OsuModDifficultyAdjust(),
                     };
 
                 case ModType.Automation:
@@ -178,7 +179,7 @@ namespace osu.Game.Rulesets.Osu
 
         public override ISkin CreateLegacySkinProvider(ISkinSource source) => new OsuLegacySkinTransformer(source);
 
-        public override int? LegacyID => 0;
+        public int LegacyID => 0;
 
         public override IConvertibleReplayFrame CreateConvertibleReplayFrame() => new OsuReplayFrame();
 

osu.Game.Rulesets.Taiko.Tests.iOS/Application.cs

@@ -5,7 +5,7 @@ using UIKit;
 
 namespace osu.Game.Rulesets.Taiko.Tests.iOS
 {
-    public class Application
+    public static class Application
     {
         public static void Main(string[] args)
         {

osu.Game.Rulesets.Taiko.Tests/.vscode/launch.json

@@ -7,7 +7,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Debug/netcoreapp3.0/osu.Game.Rulesets.Taiko.Tests.dll"
+                "${workspaceRoot}/bin/Debug/netcoreapp3.1/osu.Game.Rulesets.Taiko.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Debug)",
@@ -20,7 +20,7 @@
             "request": "launch",
             "program": "dotnet",
             "args": [
-                "${workspaceRoot}/bin/Release/netcoreapp3.0/osu.Game.Rulesets.Taiko.Tests.dll"
+                "${workspaceRoot}/bin/Release/netcoreapp3.1/osu.Game.Rulesets.Taiko.Tests.dll"
             ],
             "cwd": "${workspaceRoot}",
             "preLaunchTask": "Build (Release)",

osu.Game.Rulesets.Taiko.Tests/osu.Game.Rulesets.Taiko.Tests.csproj

@@ -9,7 +9,7 @@
   </ItemGroup>
   <PropertyGroup Label="Project">
     <OutputType>WinExe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\osu.Game.Rulesets.Taiko\osu.Game.Rulesets.Taiko.csproj" />

osu.Game.Rulesets.Taiko/Beatmaps/TaikoBeatmapConverter.cs

@@ -39,14 +39,14 @@ namespace osu.Game.Rulesets.Taiko.Beatmaps
 
         private readonly bool isForCurrentRuleset;
 
-        protected override IEnumerable<Type> ValidConversionTypes { get; } = new[] { typeof(HitObject) };
+        public TaikoBeatmapConverter(IBeatmap beatmap, Ruleset ruleset)
-
+            : base(beatmap, ruleset)
-        public TaikoBeatmapConverter(IBeatmap beatmap)
-            : base(beatmap)
         {
-            isForCurrentRuleset = beatmap.BeatmapInfo.Ruleset.Equals(new TaikoRuleset().RulesetInfo);
+            isForCurrentRuleset = beatmap.BeatmapInfo.Ruleset.Equals(ruleset.RulesetInfo);
         }
 
+        public override bool CanConvert() => true;
+
         protected override Beatmap<TaikoHitObject> ConvertBeatmap(IBeatmap original)
         {
             // Rewrite the beatmap info to add the slider velocity multiplier

osu.Game.Rulesets.Taiko/Mods/TaikoModDifficultyAdjust.cs

@@ -0,0 +1,11 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Game.Rulesets.Mods;
+
+namespace osu.Game.Rulesets.Taiko.Mods
+{
+    public class TaikoModDifficultyAdjust : ModDifficultyAdjust
+    {
+    }
+}

osu.Game.Rulesets.Taiko/TaikoRuleset.cs

@@ -24,7 +24,7 @@ using System;
 
 namespace osu.Game.Rulesets.Taiko
 {
-    public class TaikoRuleset : Ruleset
+    public class TaikoRuleset : Ruleset, ILegacyRuleset
     {
         public override DrawableRuleset CreateDrawableRulesetWith(IBeatmap beatmap, IReadOnlyList<Mod> mods = null) => new DrawableTaikoRuleset(this, beatmap, mods);
 
@@ -32,7 +32,8 @@ namespace osu.Game.Rulesets.Taiko
 
         public override HealthProcessor CreateHealthProcessor(IBeatmap beatmap) => new TaikoHealthProcessor(beatmap);
 
-        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new TaikoBeatmapConverter(beatmap);
+        public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new TaikoBeatmapConverter(beatmap, this);
+
 
         public const string SHORT_NAME = "taiko";
 
@@ -107,6 +108,12 @@ namespace osu.Game.Rulesets.Taiko
                         new TaikoModFlashlight(),
                     };
 
+                case ModType.Conversion:
+                    return new Mod[]
+                    {
+                        new TaikoModDifficultyAdjust(),
+                    };
+
                 case ModType.Automation:
                     return new Mod[]
                     {
@@ -135,7 +142,7 @@ namespace osu.Game.Rulesets.Taiko
 
         public override PerformanceCalculator CreatePerformanceCalculator(WorkingBeatmap beatmap, ScoreInfo score) => new TaikoPerformanceCalculator(this, beatmap, score);
 
-        public override int? LegacyID => 1;
+        public int LegacyID => 1;
 
         public override IConvertibleReplayFrame CreateConvertibleReplayFrame() => new TaikoReplayFrame();
     }

osu.Game.Tests.iOS/Application.cs

@@ -5,7 +5,7 @@ using UIKit;
 
 namespace osu.Game.Tests.iOS
 {
-    public class Application
+    public static class Application
     {
         public static void Main(string[] args)
         {

osu.Game.Tests/Beatmaps/Formats/LegacyBeatmapDecoderTest.cs

@@ -14,6 +14,7 @@ using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Beatmaps.Formats;
 using osu.Game.Beatmaps.Timing;
 using osu.Game.IO;
+using osu.Game.Rulesets.Catch;
 using osu.Game.Rulesets.Catch.Beatmaps;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Objects;
@@ -313,7 +314,7 @@ namespace osu.Game.Tests.Beatmaps.Formats
             {
                 var beatmap = decoder.Decode(stream);
 
-                var converted = new OsuBeatmapConverter(beatmap).Convert();
+                var converted = new OsuBeatmapConverter(beatmap, new OsuRuleset()).Convert();
                 new OsuBeatmapProcessor(converted).PreProcess();
                 new OsuBeatmapProcessor(converted).PostProcess();
 
@@ -336,7 +337,7 @@ namespace osu.Game.Tests.Beatmaps.Formats
             {
                 var beatmap = decoder.Decode(stream);
 
-                var converted = new CatchBeatmapConverter(beatmap).Convert();
+                var converted = new CatchBeatmapConverter(beatmap, new CatchRuleset()).Convert();
                 new CatchBeatmapProcessor(converted).PreProcess();
                 new CatchBeatmapProcessor(converted).PostProcess();
 

osu.Game.Tests/Beatmaps/Formats/LegacyStoryboardDecoderTest.cs

@@ -71,7 +71,7 @@ namespace osu.Game.Tests.Beatmaps.Formats
                 Assert.AreEqual(new Vector2(320, 240), sprite.InitialPosition);
                 Assert.IsTrue(sprite.IsDrawable);
                 Assert.AreEqual(Anchor.Centre, sprite.Origin);
-                Assert.AreEqual("SB/black.jpg", sprite.Path);
+                Assert.AreEqual("SB/lyric/ja-21.png", sprite.Path);
 
                 var animation = background.Elements.OfType<StoryboardAnimation>().First();
                 Assert.NotNull(animation);

osu.Game.Tests/Gameplay/TestSceneHitObjectAccentColour.cs

@@ -130,7 +130,7 @@ namespace osu.Game.Tests.Gameplay
                         switch (global)
                         {
                             case GlobalSkinConfiguration.ComboColours:
-                                return SkinUtils.As<TValue>(new Bindable<List<Color4>>(ComboColours));
+                                return SkinUtils.As<TValue>(new Bindable<IReadOnlyList<Color4>>(ComboColours));
                         }
 
                         break;

osu.Game.Tests/Skins/LegacySkinDecoderTest.cs

@@ -13,31 +13,22 @@ namespace osu.Game.Tests.Skins
     [TestFixture]
     public class LegacySkinDecoderTest
     {
-        [TestCase(true)]
+        [Test]
-        [TestCase(false)]
+        public void TestDecodeSkinColours()
-        public void TestDecodeSkinColours(bool hasColours)
         {
             var decoder = new LegacySkinDecoder();
 
-            using (var resStream = TestResources.OpenResource(hasColours ? "skin.ini" : "skin-empty.ini"))
+            using (var resStream = TestResources.OpenResource("skin.ini"))
             using (var stream = new LineBufferedReader(resStream))
             {
                 var comboColors = decoder.Decode(stream).ComboColours;
-
+                var expectedColors = new List<Color4>
-                List<Color4> expectedColors;
-
-                if (hasColours)
                 {
-                    expectedColors = new List<Color4>
+                    new Color4(142, 199, 255, 255),
-                    {
+                    new Color4(255, 128, 128, 255),
-                        new Color4(142, 199, 255, 255),
+                    new Color4(128, 255, 255, 255),
-                        new Color4(255, 128, 128, 255),
+                    new Color4(100, 100, 100, 100),
-                        new Color4(128, 255, 255, 255),
+                };
-                        new Color4(100, 100, 100, 100),
-                    };
-                }
-                else
-                    expectedColors = new DefaultSkin().Configuration.ComboColours;
 
                 Assert.AreEqual(expectedColors.Count, comboColors.Count);
                 for (int i = 0; i < expectedColors.Count; i++)
@@ -45,6 +36,37 @@ namespace osu.Game.Tests.Skins
             }
         }
 
+        [Test]
+        public void TestDecodeEmptySkinColours()
+        {
+            var decoder = new LegacySkinDecoder();
+
+            using (var resStream = TestResources.OpenResource("skin-empty.ini"))
+            using (var stream = new LineBufferedReader(resStream))
+            {
+                var comboColors = decoder.Decode(stream).ComboColours;
+                var expectedColors = SkinConfiguration.DefaultComboColours;
+
+                Assert.AreEqual(expectedColors.Count, comboColors.Count);
+                for (int i = 0; i < expectedColors.Count; i++)
+                    Assert.AreEqual(expectedColors[i], comboColors[i]);
+            }
+        }
+
+        [Test]
+        public void TestDecodeEmptySkinColoursNoFallback()
+        {
+            var decoder = new LegacySkinDecoder();
+
+            using (var resStream = TestResources.OpenResource("skin-empty.ini"))
+            using (var stream = new LineBufferedReader(resStream))
+            {
+                var skinConfiguration = decoder.Decode(stream);
+                skinConfiguration.AllowDefaultComboColoursFallback = false;
+                Assert.IsNull(skinConfiguration.ComboColours);
+            }
+        }
+
         [Test]
         public void TestDecodeGeneral()
         {

osu.Game.Tests/Skins/TestSceneSkinConfigurationLookup.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
+using System.Linq;
 using NUnit.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Audio.Sample;
@@ -21,8 +22,8 @@ namespace osu.Game.Tests.Skins
     [HeadlessTest]
     public class TestSceneSkinConfigurationLookup : OsuTestScene
     {
-        private LegacySkin source1;
+        private SkinSource source1;
-        private LegacySkin source2;
+        private SkinSource source2;
         private SkinRequester requester;
 
         [SetUp]
@@ -94,7 +95,7 @@ namespace osu.Game.Tests.Skins
         [Test]
         public void TestGlobalLookup()
         {
-            AddAssert("Check combo colours", () => requester.GetConfig<GlobalSkinConfiguration, List<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value?.Count > 0);
+            AddAssert("Check combo colours", () => requester.GetConfig<GlobalSkinConfiguration, IReadOnlyList<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value?.Count > 0);
         }
 
         [Test]
@@ -116,6 +117,28 @@ namespace osu.Game.Tests.Skins
             });
         }
 
+        [Test]
+        public void TestEmptyComboColours()
+        {
+            AddAssert("Check retrieved combo colours is skin default colours", () =>
+                requester.GetConfig<GlobalSkinConfiguration, IReadOnlyList<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value?.SequenceEqual(SkinConfiguration.DefaultComboColours) ?? false);
+        }
+
+        [Test]
+        public void TestEmptyComboColoursNoFallback()
+        {
+            AddStep("Add custom combo colours to source1", () => source1.Configuration.AddComboColours(
+                new Color4(100, 150, 200, 255),
+                new Color4(55, 110, 166, 255),
+                new Color4(75, 125, 175, 255)
+            ));
+
+            AddStep("Disallow default colours fallback in source2", () => source2.Configuration.AllowDefaultComboColoursFallback = false);
+
+            AddAssert("Check retrieved combo colours from source1", () =>
+                requester.GetConfig<GlobalSkinConfiguration, IReadOnlyList<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value?.SequenceEqual(source1.Configuration.ComboColours) ?? false);
+        }
+
         [Test]
         public void TestLegacyVersionLookup()
         {

osu.Game.Tests/Visual/Editor/TestSceneEditorComposeTimeline.cs

@@ -68,8 +68,11 @@ namespace osu.Game.Tests.Visual.Editor
         {
             private readonly Drawable marker;
 
-            private readonly IBindable<WorkingBeatmap> beatmap = new Bindable<WorkingBeatmap>();
+            [Resolved]
-            private IAdjustableClock adjustableClock;
+            private IBindable<WorkingBeatmap> beatmap { get; set; }
+
+            [Resolved]
+            private IAdjustableClock adjustableClock { get; set; }
 
             public AudioVisualiser()
             {
@@ -91,13 +94,6 @@ namespace osu.Game.Tests.Visual.Editor
                 };
             }
 
-            [BackgroundDependencyLoader]
-            private void load(IAdjustableClock adjustableClock, IBindable<WorkingBeatmap> beatmap)
-            {
-                this.adjustableClock = adjustableClock;
-                this.beatmap.BindTo(beatmap);
-            }
-
             protected override void Update()
             {
                 base.Update();

osu.Game.Tests/Visual/Gameplay/TestSceneDrawableScrollingRuleset.cs

@@ -198,7 +198,7 @@ namespace osu.Game.Tests.Visual.Gameplay
 
             public override DrawableRuleset CreateDrawableRulesetWith(IBeatmap beatmap, IReadOnlyList<Mod> mods = null) => new TestDrawableScrollingRuleset(this, beatmap, mods);
 
-            public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new TestBeatmapConverter(beatmap);
+            public override IBeatmapConverter CreateBeatmapConverter(IBeatmap beatmap) => new TestBeatmapConverter(beatmap, null);
 
             public override DifficultyCalculator CreateDifficultyCalculator(WorkingBeatmap beatmap) => throw new NotImplementedException();
 
@@ -268,12 +268,12 @@ namespace osu.Game.Tests.Visual.Gameplay
 
         private class TestBeatmapConverter : BeatmapConverter<TestHitObject>
         {
-            public TestBeatmapConverter(IBeatmap beatmap)
+            public TestBeatmapConverter(IBeatmap beatmap, Ruleset ruleset)
-                : base(beatmap)
+                : base(beatmap, ruleset)
             {
             }
 
-            protected override IEnumerable<Type> ValidConversionTypes => new[] { typeof(HitObject) };
+            public override bool CanConvert() => true;
 
             protected override IEnumerable<TestHitObject> ConvertHitObject(HitObject original, IBeatmap beatmap)
             {

osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapDetailArea.cs

@@ -1,237 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using NUnit.Framework;
-using osu.Framework.Allocation;
-using osu.Framework.Graphics;
-using osu.Game.Beatmaps;
-using osu.Game.Rulesets;
-using osu.Game.Rulesets.Mods;
-using osu.Game.Screens.Play.HUD;
-using osu.Game.Screens.Select;
-using osu.Game.Tests.Beatmaps;
-using osuTK;
-
-namespace osu.Game.Tests.Visual.SongSelect
-{
-    [TestFixture]
-    [System.ComponentModel.Description("PlaySongSelect leaderboard/details area")]
-    public class TestSceneBeatmapDetailArea : OsuTestScene
-    {
-        public override IReadOnlyList<Type> RequiredTypes => new[] { typeof(BeatmapDetails) };
-
-        private ModDisplay modDisplay;
-
-        [BackgroundDependencyLoader]
-        private void load(OsuGameBase game, RulesetStore rulesets)
-        {
-            BeatmapDetailArea detailsArea;
-            Add(detailsArea = new BeatmapDetailArea
-            {
-                Anchor = Anchor.Centre,
-                Origin = Anchor.Centre,
-                Size = new Vector2(550f, 450f),
-            });
-
-            Add(modDisplay = new ModDisplay
-            {
-                Anchor = Anchor.TopRight,
-                Origin = Anchor.TopRight,
-                AutoSizeAxes = Axes.Both,
-                Position = new Vector2(0, 25),
-            });
-
-            modDisplay.Current.BindTo(SelectedMods);
-
-            AddStep("all metrics", () => detailsArea.Beatmap = new TestWorkingBeatmap(new Beatmap
-            {
-                BeatmapInfo =
-                {
-                    BeatmapSet = new BeatmapSetInfo
-                    {
-                        Metrics = new BeatmapSetMetrics { Ratings = Enumerable.Range(0, 11).ToArray() }
-                    },
-                    Version = "All Metrics",
-                    Metadata = new BeatmapMetadata
-                    {
-                        Source = "osu!lazer",
-                        Tags = "this beatmap has all the metrics",
-                    },
-                    BaseDifficulty = new BeatmapDifficulty
-                    {
-                        CircleSize = 7,
-                        DrainRate = 1,
-                        OverallDifficulty = 5.7f,
-                        ApproachRate = 3.5f,
-                    },
-                    StarDifficulty = 5.3f,
-                    Metrics = new BeatmapMetrics
-                    {
-                        Fails = Enumerable.Range(1, 100).Select(i => i % 12 - 6).ToArray(),
-                        Retries = Enumerable.Range(-2, 100).Select(i => i % 12 - 6).ToArray(),
-                    },
-                }
-            }));
-
-            AddStep("all except source", () => detailsArea.Beatmap = new TestWorkingBeatmap(new Beatmap
-            {
-                BeatmapInfo =
-                {
-                    BeatmapSet = new BeatmapSetInfo
-                    {
-                        Metrics = new BeatmapSetMetrics { Ratings = Enumerable.Range(0, 11).ToArray() }
-                    },
-                    Version = "All Metrics",
-                    Metadata = new BeatmapMetadata
-                    {
-                        Tags = "this beatmap has all the metrics",
-                    },
-                    BaseDifficulty = new BeatmapDifficulty
-                    {
-                        CircleSize = 7,
-                        DrainRate = 1,
-                        OverallDifficulty = 5.7f,
-                        ApproachRate = 3.5f,
-                    },
-                    StarDifficulty = 5.3f,
-                    Metrics = new BeatmapMetrics
-                    {
-                        Fails = Enumerable.Range(1, 100).Select(i => i % 12 - 6).ToArray(),
-                        Retries = Enumerable.Range(-2, 100).Select(i => i % 12 - 6).ToArray(),
-                    },
-                }
-            }));
-
-            AddStep("ratings", () => detailsArea.Beatmap = new TestWorkingBeatmap(new Beatmap
-            {
-                BeatmapInfo =
-                {
-                    BeatmapSet = new BeatmapSetInfo
-                    {
-                        Metrics = new BeatmapSetMetrics { Ratings = Enumerable.Range(0, 11).ToArray() }
-                    },
-                    Version = "Only Ratings",
-                    Metadata = new BeatmapMetadata
-                    {
-                        Source = "osu!lazer",
-                        Tags = "this beatmap has ratings metrics but not retries or fails",
-                    },
-                    BaseDifficulty = new BeatmapDifficulty
-                    {
-                        CircleSize = 6,
-                        DrainRate = 9,
-                        OverallDifficulty = 6,
-                        ApproachRate = 6,
-                    },
-                    StarDifficulty = 4.8f
-                }
-            }));
-
-            AddStep("fails+retries", () => detailsArea.Beatmap = new TestWorkingBeatmap(new Beatmap
-            {
-                BeatmapInfo =
-                {
-                    Version = "Only Retries and Fails",
-                    Metadata = new BeatmapMetadata
-                    {
-                        Source = "osu!lazer",
-                        Tags = "this beatmap has retries and fails but no ratings",
-                    },
-                    BaseDifficulty = new BeatmapDifficulty
-                    {
-                        CircleSize = 3.7f,
-                        DrainRate = 6,
-                        OverallDifficulty = 6,
-                        ApproachRate = 7,
-                    },
-                    StarDifficulty = 2.91f,
-                    Metrics = new BeatmapMetrics
-                    {
-                        Fails = Enumerable.Range(1, 100).Select(i => i % 12 - 6).ToArray(),
-                        Retries = Enumerable.Range(-2, 100).Select(i => i % 12 - 6).ToArray(),
-                    },
-                }
-            }));
-
-            AddStep("null metrics", () => detailsArea.Beatmap = new TestWorkingBeatmap(new Beatmap
-            {
-                BeatmapInfo =
-                {
-                    Version = "No Metrics",
-                    Metadata = new BeatmapMetadata
-                    {
-                        Source = "osu!lazer",
-                        Tags = "this beatmap has no metrics",
-                    },
-                    BaseDifficulty = new BeatmapDifficulty
-                    {
-                        CircleSize = 5,
-                        DrainRate = 5,
-                        OverallDifficulty = 5.5f,
-                        ApproachRate = 6.5f,
-                    },
-                    StarDifficulty = 1.97f,
-                }
-            }));
-
-            AddStep("null beatmap", () => detailsArea.Beatmap = null);
-
-            Ruleset ruleset = rulesets.AvailableRulesets.First().CreateInstance();
-
-            AddStep("with EZ mod", () =>
-            {
-                detailsArea.Beatmap = new TestWorkingBeatmap(new Beatmap
-                {
-                    BeatmapInfo =
-                    {
-                        Version = "Has Easy Mod",
-                        Metadata = new BeatmapMetadata
-                        {
-                            Source = "osu!lazer",
-                            Tags = "this beatmap has the easy mod enabled",
-                        },
-                        BaseDifficulty = new BeatmapDifficulty
-                        {
-                            CircleSize = 3,
-                            DrainRate = 3,
-                            OverallDifficulty = 3,
-                            ApproachRate = 3,
-                        },
-                        StarDifficulty = 1f,
-                    }
-                });
-
-                SelectedMods.Value = new[] { ruleset.GetAllMods().First(m => m is ModEasy) };
-            });
-
-            AddStep("with HR mod", () =>
-            {
-                detailsArea.Beatmap = new TestWorkingBeatmap(new Beatmap
-                {
-                    BeatmapInfo =
-                    {
-                        Version = "Has Hard Rock Mod",
-                        Metadata = new BeatmapMetadata
-                        {
-                            Source = "osu!lazer",
-                            Tags = "this beatmap has the hard rock mod enabled",
-                        },
-                        BaseDifficulty = new BeatmapDifficulty
-                        {
-                            CircleSize = 3,
-                            DrainRate = 3,
-                            OverallDifficulty = 3,
-                            ApproachRate = 3,
-                        },
-                        StarDifficulty = 1f,
-                    }
-                });
-
-                SelectedMods.Value = new[] { ruleset.GetAllMods().First(m => m is ModHardRock) };
-            });
-        }
-    }
-}

osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapDetails.cs

@@ -3,8 +3,14 @@
 
 using System.Linq;
 using NUnit.Framework;
+using osu.Framework.Allocation;
 using osu.Framework.Graphics;
+using osu.Framework.Testing;
 using osu.Game.Beatmaps;
+using osu.Game.Graphics;
+using osu.Game.Graphics.UserInterface;
+using osu.Game.Rulesets;
+using osu.Game.Rulesets.Mods;
 using osu.Game.Screens.Select;
 
 namespace osu.Game.Tests.Visual.SongSelect
@@ -174,5 +180,27 @@ namespace osu.Game.Tests.Visual.SongSelect
                 OnlineBeatmapID = 162,
             });
         }
+
+        [Resolved]
+        private RulesetStore rulesets { get; set; }
+
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        [Test]
+        public void TestModAdjustments()
+        {
+            TestAllMetrics();
+
+            Ruleset ruleset = rulesets.AvailableRulesets.First().CreateInstance();
+
+            AddStep("with EZ mod", () => SelectedMods.Value = new[] { ruleset.GetAllMods().First(m => m is ModEasy) });
+
+            AddAssert("first bar coloured blue", () => details.ChildrenOfType<Bar>().Skip(1).First().AccentColour == colours.BlueDark);
+
+            AddStep("with HR mod", () => SelectedMods.Value = new[] { ruleset.GetAllMods().First(m => m is ModHardRock) });
+
+            AddAssert("first bar coloured red", () => details.ChildrenOfType<Bar>().Skip(1).First().AccentColour == colours.Red);
+        }
     }
 }

osu.Game.Tests/WaveformTestBeatmap.cs

@@ -20,26 +20,24 @@ namespace osu.Game.Tests
     /// </summary>
     public class WaveformTestBeatmap : WorkingBeatmap
     {
-        private readonly ZipArchiveReader reader;
-        private readonly Stream stream;
         private readonly ITrackStore trackStore;
 
         public WaveformTestBeatmap(AudioManager audioManager)
             : base(new BeatmapInfo(), audioManager)
         {
-            stream = TestResources.GetTestBeatmapStream();
+            trackStore = audioManager.GetTrackStore(getZipReader());
-            reader = new ZipArchiveReader(stream);
-            trackStore = audioManager.GetTrackStore(reader);
         }
 
         protected override void Dispose(bool isDisposing)
         {
             base.Dispose(isDisposing);
-            stream?.Dispose();
-            reader?.Dispose();
             trackStore?.Dispose();
         }
 
+        private Stream getStream() => TestResources.GetTestBeatmapStream();
+
+        private ZipArchiveReader getZipReader() => new ZipArchiveReader(getStream());
+
         protected override IBeatmap GetBeatmap() => createTestBeatmap();
 
         protected override Texture GetBackground() => null;
@@ -50,15 +48,23 @@ namespace osu.Game.Tests
 
         protected override Track GetTrack() => trackStore.Get(firstAudioFile);
 
-        private string firstAudioFile => reader.Filenames.First(f => f.EndsWith(".mp3"));
+        private string firstAudioFile
-
+        {
-        private Stream getBeatmapStream() => reader.GetStream(reader.Filenames.First(f => f.EndsWith(".osu")));
+            get
+            {
+                using (var reader = getZipReader())
+                    return reader.Filenames.First(f => f.EndsWith(".mp3"));
+            }
+        }
 
         private Beatmap createTestBeatmap()
         {
-            using (var beatmapStream = getBeatmapStream())
+            using (var reader = getZipReader())
-            using (var beatmapReader = new LineBufferedReader(beatmapStream))
+            {
-                return Decoder.GetDecoder<Beatmap>(beatmapReader).Decode(beatmapReader);
+                using (var beatmapStream = reader.GetStream(reader.Filenames.First(f => f.EndsWith(".osu"))))
+                using (var beatmapReader = new LineBufferedReader(beatmapStream))
+                    return Decoder.GetDecoder<Beatmap>(beatmapReader).Decode(beatmapReader);
+            }
         }
     }
 }

osu.Game.Tests/osu.Game.Tests.csproj

@@ -10,7 +10,7 @@
   </ItemGroup>
   <PropertyGroup Label="Project">
     <OutputType>WinExe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\osu.Game.Rulesets.Osu\osu.Game.Rulesets.Osu.csproj" />

osu.Game.Tournament.Tests/osu.Game.Tournament.Tests.csproj

@@ -11,7 +11,7 @@
   </ItemGroup>
   <PropertyGroup Label="Project">
     <OutputType>WinExe</OutputType>
-    <TargetFramework>netcoreapp3.0</TargetFramework>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
   </PropertyGroup>
   <ItemGroup Label="Project References">
     <ProjectReference Include="..\osu.Game.Rulesets.Catch\osu.Game.Rulesets.Catch.csproj" />

osu.Game/Beatmaps/BeatmapConverter.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using osu.Game.Rulesets;
 using osu.Game.Rulesets.Objects;
 
 namespace osu.Game.Beatmaps
@@ -25,7 +26,7 @@ namespace osu.Game.Beatmaps
 
         public IBeatmap Beatmap { get; }
 
-        protected BeatmapConverter(IBeatmap beatmap)
+        protected BeatmapConverter(IBeatmap beatmap, Ruleset ruleset)
         {
             Beatmap = beatmap;
         }
@@ -33,7 +34,7 @@ namespace osu.Game.Beatmaps
         /// <summary>
         /// Whether <see cref="Beatmap"/> can be converted by this <see cref="BeatmapConverter{T}"/>.
         /// </summary>
-        public bool CanConvert => !Beatmap.HitObjects.Any() || ValidConversionTypes.All(t => Beatmap.HitObjects.Any(t.IsInstanceOfType));
+        public abstract bool CanConvert();
 
         /// <summary>
         /// Converts <see cref="Beatmap"/>.
@@ -92,11 +93,6 @@ namespace osu.Game.Beatmaps
             return result;
         }
 
-        /// <summary>
-        /// The types of HitObjects that can be converted to be used for this Beatmap.
-        /// </summary>
-        protected abstract IEnumerable<Type> ValidConversionTypes { get; }
-
         /// <summary>
         /// Creates the <see cref="Beatmap{T}"/> that will be returned by this <see cref="BeatmapProcessor"/>.
         /// </summary>

osu.Game/Beatmaps/DummyWorkingBeatmap.cs

@@ -76,7 +76,7 @@ namespace osu.Game.Beatmaps
 
                     public IBeatmap Beatmap { get; set; }
 
-                    public bool CanConvert => true;
+                    public bool CanConvert() => true;
 
                     public IBeatmap Convert()
                     {

osu.Game/Beatmaps/Formats/IHasComboColours.cs

@@ -8,6 +8,14 @@ namespace osu.Game.Beatmaps.Formats
 {
     public interface IHasComboColours
     {
-        List<Color4> ComboColours { get; set; }
+        /// <summary>
+        /// Retrieves the list of combo colours for presentation only.
+        /// </summary>
+        IReadOnlyList<Color4> ComboColours { get; }
+
+        /// <summary>
+        /// Adds combo colours to the list.
+        /// </summary>
+        void AddComboColours(params Color4[] colours);
     }
 }

osu.Game/Beatmaps/Formats/LegacyDecoder.cs

@@ -77,8 +77,6 @@ namespace osu.Game.Beatmaps.Formats
             return line;
         }
 
-        private bool hasComboColours;
-
         private void handleColours(T output, string line)
         {
             var pair = SplitKeyVal(line);
@@ -105,14 +103,7 @@ namespace osu.Game.Beatmaps.Formats
             {
                 if (!(output is IHasComboColours tHasComboColours)) return;
 
-                if (!hasComboColours)
+                tHasComboColours.AddComboColours(colour);
-                {
-                    // remove default colours.
-                    tHasComboColours.ComboColours.Clear();
-                    hasComboColours = true;
-                }
-
-                tHasComboColours.ComboColours.Add(colour);
             }
             else
             {

osu.Game/Beatmaps/Formats/LegacyStoryboardDecoder.cs

@@ -5,7 +5,6 @@ using System;
 using System.Collections.Generic;
 using System.Globalization;
 using System.IO;
-using System.Linq;
 using osuTK;
 using osuTK.Graphics;
 using osu.Framework.Extensions;
@@ -42,10 +41,6 @@ namespace osu.Game.Beatmaps.Formats
         {
             this.storyboard = storyboard;
             base.ParseStreamInto(stream, storyboard);
-
-            // OrderBy is used to guarantee that the parsing order of elements with equal start times is maintained (stably-sorted)
-            foreach (StoryboardLayer layer in storyboard.Layers)
-                layer.Elements = layer.Elements.OrderBy(h => h.StartTime).ToList();
         }
 
         protected override void ParseLine(Storyboard storyboard, Section section, string line)

osu.Game/Beatmaps/IBeatmapConverter.cs

@@ -25,7 +25,7 @@ namespace osu.Game.Beatmaps
         /// <summary>
         /// Whether <see cref="Beatmap"/> can be converted by this <see cref="IBeatmapConverter"/>.
         /// </summary>
-        bool CanConvert { get; }
+        bool CanConvert();
 
         /// <summary>
         /// Converts <see cref="Beatmap"/>.

osu.Game/Beatmaps/WorkingBeatmap.cs

@@ -108,7 +108,7 @@ namespace osu.Game.Beatmaps
             IBeatmapConverter converter = CreateBeatmapConverter(Beatmap, rulesetInstance);
 
             // Check if the beatmap can be converted
-            if (!converter.CanConvert)
+            if (Beatmap.HitObjects.Count > 0 && !converter.CanConvert())
                 throw new BeatmapInvalidForRulesetException($"{nameof(Beatmaps.Beatmap)} can not be converted for the ruleset (ruleset: {ruleset.InstantiationInfo}, converter: {converter}).");
 
             // Apply conversion mods

osu.Game/Graphics/UserInterface/BreadcrumbControl.cs

@@ -52,7 +52,6 @@ namespace osu.Game.Graphics.UserInterface
 
             public override bool HandleNonPositionalInput => State == Visibility.Visible;
             public override bool HandlePositionalInput => State == Visibility.Visible;
-            public override bool IsRemovable => true;
 
             private Visibility state;
 

osu.Game/Graphics/UserInterface/OsuTextBox.cs

@@ -12,10 +12,12 @@ using osu.Framework.Input.Events;
 
 namespace osu.Game.Graphics.UserInterface
 {
-    public class OsuTextBox : TextBox
+    public class OsuTextBox : BasicTextBox
     {
         protected override float LeftRightPadding => 10;
 
+        protected override float CaretWidth => 3;
+
         protected override SpriteText CreatePlaceholder() => new OsuSpriteText
         {
             Font = OsuFont.GetFont(italics: true),
@@ -41,6 +43,8 @@ namespace osu.Game.Graphics.UserInterface
             BackgroundCommit = BorderColour = colour.Yellow;
         }
 
+        protected override Color4 SelectionColour => new Color4(249, 90, 255, 255);
+
         protected override void OnFocus(FocusEvent e)
         {
             BorderThickness = 3;

osu.Game/Overlays/ChatOverlay.cs

@@ -171,6 +171,7 @@ namespace osu.Game.Overlays
                                     d.Origin = Anchor.BottomLeft;
                                     d.RelativeSizeAxes = Axes.Both;
                                     d.OnRequestLeave = channelManager.LeaveChannel;
+                                    d.IsSwitchable = true;
                                 }),
                             }
                         },

osu.Game/Overlays/Settings/ISettingsItem.cs

@@ -0,0 +1,13 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Framework.Graphics;
+
+namespace osu.Game.Overlays.Settings
+{
+    public interface ISettingsItem : IDrawable, IDisposable
+    {
+        event Action SettingChanged;
+    }
+}

osu.Game/Overlays/Settings/SettingsItem.cs

@@ -1,6 +1,7 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using System.Collections.Generic;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
@@ -20,7 +21,7 @@ using osuTK;
 
 namespace osu.Game.Overlays.Settings
 {
-    public abstract class SettingsItem<T> : Container, IFilterable
+    public abstract class SettingsItem<T> : Container, IFilterable, ISettingsItem
     {
         protected abstract Drawable CreateControl();
 
@@ -34,8 +35,6 @@ namespace osu.Game.Overlays.Settings
 
         private SpriteText text;
 
-        private readonly RestoreDefaultValueButton restoreDefaultButton;
-
         public bool ShowsDefaultIndicator = true;
 
         public virtual string LabelText
@@ -70,8 +69,12 @@ namespace osu.Game.Overlays.Settings
 
         public bool FilteringActive { get; set; }
 
+        public event Action SettingChanged;
+
         protected SettingsItem()
         {
+            RestoreDefaultValueButton restoreDefaultButton;
+
             RelativeSizeAxes = Axes.X;
             AutoSizeAxes = Axes.Y;
             Padding = new MarginPadding { Right = SettingsPanel.CONTENT_MARGINS };
@@ -87,13 +90,12 @@ namespace osu.Game.Overlays.Settings
                     Child = Control = CreateControl()
                 },
             };
-        }
 
-        [BackgroundDependencyLoader]
+            // all bindable logic is in constructor intentionally to support "CreateSettingsControls" being used in a context it is
-        private void load()
+            // never loaded, but requires bindable storage.
-        {
             if (controlWithCurrent != null)
             {
+                controlWithCurrent.Current.ValueChanged += _ => SettingChanged?.Invoke();
                 controlWithCurrent.Current.DisabledChanged += disabled => { Colour = disabled ? Color4.Gray : Color4.White; };
 
                 if (ShowsDefaultIndicator)
@@ -113,6 +115,7 @@ namespace osu.Game.Overlays.Settings
                     bindable = value;
                     bindable.ValueChanged += _ => UpdateState();
                     bindable.DisabledChanged += _ => UpdateState();
+                    bindable.DefaultChanged += _ => UpdateState();
                     UpdateState();
                 }
             }

osu.Game/Rulesets/ILegacyRuleset.cs

@@ -0,0 +1,13 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+namespace osu.Game.Rulesets
+{
+    public interface ILegacyRuleset
+    {
+        /// <summary>
+        /// Identifies the server-side ID of a legacy ruleset.
+        /// </summary>
+        int LegacyID { get; }
+    }
+}

osu.Game/Rulesets/Mods/ModDifficultyAdjust.cs

@@ -0,0 +1,81 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Game.Beatmaps;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics.Sprites;
+using System;
+using osu.Game.Configuration;
+
+namespace osu.Game.Rulesets.Mods
+{
+    public abstract class ModDifficultyAdjust : Mod, IApplicableToDifficulty
+    {
+        public override string Name => @"Difficulty Adjust";
+
+        public override string Description => @"Override a beatmap's difficulty settings.";
+
+        public override string Acronym => "DA";
+
+        public override ModType Type => ModType.Conversion;
+
+        public override IconUsage Icon => FontAwesome.Solid.Hammer;
+
+        public override double ScoreMultiplier => 1.0;
+
+        public override Type[] IncompatibleMods => new[] { typeof(ModEasy), typeof(ModHardRock) };
+
+        [SettingSource("Drain Rate", "Override a beatmap's set HP.")]
+        public BindableNumber<float> DrainRate { get; } = new BindableFloat
+        {
+            Precision = 0.1f,
+            MinValue = 1,
+            MaxValue = 10,
+            Default = 5,
+            Value = 5,
+        };
+
+        [SettingSource("Overall Difficulty", "Override a beatmap's set OD.")]
+        public BindableNumber<float> OverallDifficulty { get; } = new BindableFloat
+        {
+            Precision = 0.1f,
+            MinValue = 1,
+            MaxValue = 10,
+            Default = 5,
+            Value = 5,
+        };
+
+        private BeatmapDifficulty difficulty;
+
+        public void ApplyToDifficulty(BeatmapDifficulty difficulty)
+        {
+            if (this.difficulty == null || this.difficulty.ID != difficulty.ID)
+            {
+                this.difficulty = difficulty;
+                TransferSettings(difficulty);
+            }
+            else
+                ApplySettings(difficulty);
+        }
+
+        /// <summary>
+        /// Transfer initial settings from the beatmap to settings.
+        /// </summary>
+        /// <param name="difficulty">The beatmap's initial values.</param>
+        protected virtual void TransferSettings(BeatmapDifficulty difficulty)
+        {
+            DrainRate.Value = DrainRate.Default = difficulty.DrainRate;
+            OverallDifficulty.Value = OverallDifficulty.Default = difficulty.OverallDifficulty;
+        }
+
+        /// <summary>
+        /// Apply all custom settings to the provided beatmap.
+        /// </summary>
+        /// <param name="difficulty">The beatmap to have settings applied.</param>
+        protected virtual void ApplySettings(BeatmapDifficulty difficulty)
+        {
+            difficulty.DrainRate = DrainRate.Value;
+            difficulty.OverallDifficulty = OverallDifficulty.Value;
+        }
+    }
+}

osu.Game/Rulesets/Mods/ModEasy.cs

@@ -5,6 +5,7 @@ using System;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics.Sprites;
 using osu.Game.Beatmaps;
+using osu.Game.Configuration;
 using osu.Game.Graphics;
 using osu.Game.Rulesets.Scoring;
 
@@ -18,9 +19,16 @@ namespace osu.Game.Rulesets.Mods
         public override ModType Type => ModType.DifficultyReduction;
         public override double ScoreMultiplier => 0.5;
         public override bool Ranked => true;
-        public override Type[] IncompatibleMods => new[] { typeof(ModHardRock) };
+        public override Type[] IncompatibleMods => new[] { typeof(ModHardRock), typeof(ModDifficultyAdjust) };
 
-        private int retries = 2;
+        [SettingSource("Extra Lives", "Number of extra lives")]
+        public Bindable<int> Retries { get; } = new BindableInt(2)
+        {
+            MinValue = 0,
+            MaxValue = 10
+        };
+
+        private int retries;
 
         private BindableNumber<double> health;
 
@@ -31,6 +39,8 @@ namespace osu.Game.Rulesets.Mods
             difficulty.ApproachRate *= ratio;
             difficulty.DrainRate *= ratio;
             difficulty.OverallDifficulty *= ratio;
+
+            retries = Retries.Value;
         }
 
         public bool AllowFail

osu.Game/Rulesets/Mods/ModHardRock.cs

@@ -15,7 +15,7 @@ namespace osu.Game.Rulesets.Mods
         public override IconUsage Icon => OsuIcon.ModHardrock;
         public override ModType Type => ModType.DifficultyIncrease;
         public override string Description => "Everything just got a bit harder...";
-        public override Type[] IncompatibleMods => new[] { typeof(ModEasy) };
+        public override Type[] IncompatibleMods => new[] { typeof(ModEasy), typeof(ModDifficultyAdjust) };
 
         public void ApplyToDifficulty(BeatmapDifficulty difficulty)
         {

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -356,7 +356,7 @@ namespace osu.Game.Rulesets.Objects.Drawables
         {
             if (HitObject is IHasComboInformation combo)
             {
-                var comboColours = CurrentSkin.GetConfig<GlobalSkinConfiguration, List<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value;
+                var comboColours = CurrentSkin.GetConfig<GlobalSkinConfiguration, IReadOnlyList<Color4>>(GlobalSkinConfiguration.ComboColours)?.Value;
                 AccentColour.Value = comboColours?.Count > 0 ? comboColours[combo.ComboIndex % comboColours.Count] : Color4.White;
             }
         }

osu.Game/Rulesets/Ruleset.cs

@@ -26,7 +26,7 @@ namespace osu.Game.Rulesets
 {
     public abstract class Ruleset
     {
-        public readonly RulesetInfo RulesetInfo;
+        public RulesetInfo RulesetInfo { get; internal set; }
 
         public IEnumerable<Mod> GetAllMods() => Enum.GetValues(typeof(ModType)).Cast<ModType>()
                                                     // Confine all mods of each mod type into a single IEnumerable<Mod>
@@ -51,7 +51,14 @@ namespace osu.Game.Rulesets
 
         protected Ruleset()
         {
-            RulesetInfo = createRulesetInfo();
+            RulesetInfo = new RulesetInfo
+            {
+                Name = Description,
+                ShortName = ShortName,
+                ID = (this as ILegacyRuleset)?.LegacyID,
+                InstantiationInfo = GetType().AssemblyQualifiedName,
+                Available = true
+            };
         }
 
         /// <summary>
@@ -109,11 +116,6 @@ namespace osu.Game.Rulesets
         /// <param name="settings">The <see cref="SettingsStore"/> to store the settings.</param>
         public virtual IRulesetConfigManager CreateConfig(SettingsStore settings) => null;
 
-        /// <summary>
-        /// Do not override this unless you are a legacy mode.
-        /// </summary>
-        public virtual int? LegacyID => null;
-
         /// <summary>
         /// A unique short name to reference this ruleset in online requests.
         /// </summary>
@@ -144,18 +146,5 @@ namespace osu.Game.Rulesets
         /// </summary>
         /// <returns>An empty frame for the current ruleset, or null if unsupported.</returns>
         public virtual IConvertibleReplayFrame CreateConvertibleReplayFrame() => null;
-
-        /// <summary>
-        /// Create a ruleset info based on this ruleset.
-        /// </summary>
-        /// <returns>A filled <see cref="RulesetInfo"/>.</returns>
-        private RulesetInfo createRulesetInfo() => new RulesetInfo
-        {
-            Name = Description,
-            ShortName = ShortName,
-            InstantiationInfo = GetType().AssemblyQualifiedName,
-            ID = LegacyID,
-            Available = true
-        };
     }
 }

osu.Game/Rulesets/RulesetInfo.cs

@@ -20,11 +20,17 @@ namespace osu.Game.Rulesets
         [JsonIgnore]
         public bool Available { get; set; }
 
+        // TODO: this should probably be moved to RulesetStore.
         public virtual Ruleset CreateInstance()
         {
             if (!Available) return null;
 
-            return (Ruleset)Activator.CreateInstance(Type.GetType(InstantiationInfo));
+            var ruleset = (Ruleset)Activator.CreateInstance(Type.GetType(InstantiationInfo));
+
+            // overwrite the pre-populated RulesetInfo with a potentially database attached copy.
+            ruleset.RulesetInfo = this;
+
+            return ruleset;
         }
 
         public bool Equals(RulesetInfo other) => other != null && ID == other.ID && Available == other.Available && Name == other.Name && InstantiationInfo == other.InstantiationInfo;

osu.Game/Rulesets/RulesetStore.cs

@@ -58,17 +58,17 @@ namespace osu.Game.Rulesets
 
                 var instances = loadedAssemblies.Values.Select(r => (Ruleset)Activator.CreateInstance(r)).ToList();
 
-                //add all legacy modes in correct order
+                //add all legacy rulesets first to ensure they have exclusive choice of primary key.
-                foreach (var r in instances.Where(r => r.LegacyID != null).OrderBy(r => r.LegacyID))
+                foreach (var r in instances.Where(r => r is ILegacyRuleset))
                 {
-                    if (context.RulesetInfo.SingleOrDefault(rsi => rsi.ID == r.RulesetInfo.ID) == null)
+                    if (context.RulesetInfo.SingleOrDefault(dbRuleset => dbRuleset.ID == r.RulesetInfo.ID) == null)
                         context.RulesetInfo.Add(r.RulesetInfo);
                 }
 
                 context.SaveChanges();
 
                 //add any other modes
-                foreach (var r in instances.Where(r => r.LegacyID == null))
+                foreach (var r in instances.Where(r => !(r is ILegacyRuleset)))
                 {
                     if (context.RulesetInfo.FirstOrDefault(ri => ri.InstantiationInfo == r.RulesetInfo.InstantiationInfo) == null)
                         context.RulesetInfo.Add(r.RulesetInfo);

osu.Game/Rulesets/UI/DrawableRuleset.cs

@@ -159,7 +159,7 @@ namespace osu.Game.Rulesets.UI
                 dependencies.Cache(textureStore);
 
                 localSampleStore = dependencies.Get<AudioManager>().GetSampleStore(new NamespacedResourceStore<byte[]>(resources, "Samples"));
-                dependencies.CacheAs(new FallbackSampleStore(localSampleStore, dependencies.Get<ISampleStore>()));
+                dependencies.CacheAs<ISampleStore>(new FallbackSampleStore(localSampleStore, dependencies.Get<ISampleStore>()));
             }
 
             onScreenDisplay = dependencies.Get<OnScreenDisplay>();

osu.Game/Screens/Menu/MainMenu.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using System.Linq;
 using osuTK;
 using osuTK.Graphics;
 using osu.Framework.Allocation;
@@ -132,6 +133,8 @@ namespace osu.Game.Screens.Menu
 
         private void confirmAndExit()
         {
+            if (exitConfirmed) return;
+
             exitConfirmed = true;
             this.Exit();
         }
@@ -244,10 +247,18 @@ namespace osu.Game.Screens.Menu
 
         public override bool OnExiting(IScreen next)
         {
-            if (!exitConfirmed && dialogOverlay != null && !(dialogOverlay.CurrentDialog is ConfirmExitDialog))
+            if (!exitConfirmed && dialogOverlay != null)
             {
-                dialogOverlay.Push(new ConfirmExitDialog(confirmAndExit, () => exitConfirmOverlay.Abort()));
+                if (dialogOverlay.CurrentDialog is ConfirmExitDialog exitDialog)
-                return true;
+                {
+                    exitConfirmed = true;
+                    exitDialog.Buttons.First().Click();
+                }
+                else
+                {
+                    dialogOverlay.Push(new ConfirmExitDialog(confirmAndExit, () => exitConfirmOverlay.Abort()));
+                    return true;
+                }
             }
 
             buttons.State = ButtonSystemState.Exit;

osu.Game/Screens/Play/KeyCounterDisplay.cs

@@ -43,6 +43,11 @@ namespace osu.Game.Screens.Play
         private void load(OsuConfigManager config)
         {
             config.BindWith(OsuSetting.KeyOverlay, configVisibility);
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
 
             Visible.BindValueChanged(_ => updateVisibility());
             configVisibility.BindValueChanged(_ => updateVisibility(), true);

osu.Game/Screens/Play/Player.cs

@@ -580,7 +580,7 @@ namespace osu.Game.Screens.Play
 
             // GameplayClockContainer performs seeks / start / stop operations on the beatmap's track.
             // as we are no longer the current screen, we cannot guarantee the track is still usable.
-            GameplayClockContainer.StopUsingBeatmapClock();
+            GameplayClockContainer?.StopUsingBeatmapClock();
 
             fadeOut();
             return base.OnExiting(next);

osu.Game/Screens/Select/BeatmapDetailAreaTabControl.cs

@@ -48,6 +48,7 @@ namespace osu.Game.Screens.Select
                         Anchor = Anchor.BottomLeft,
                         Origin = Anchor.BottomLeft,
                         RelativeSizeAxes = Axes.Both,
+                        IsSwitchable = true,
                     },
                 },
                 modsCheckbox = new OsuTabControlCheckbox

osu.Game/Screens/Select/Details/AdvancedStats.cs

@@ -16,6 +16,9 @@ using osu.Framework.Bindables;
 using System.Collections.Generic;
 using osu.Game.Rulesets.Mods;
 using System.Linq;
+using osu.Framework.Threading;
+using osu.Game.Configuration;
+using osu.Game.Overlays.Settings;
 
 namespace osu.Game.Screens.Select.Details
 {
@@ -69,7 +72,37 @@ namespace osu.Game.Screens.Select.Details
         {
             base.LoadComplete();
 
-            mods.BindValueChanged(_ => updateStatistics(), true);
+            mods.BindValueChanged(modsChanged, true);
+        }
+
+        private readonly List<ISettingsItem> references = new List<ISettingsItem>();
+
+        private void modsChanged(ValueChangedEvent<IReadOnlyList<Mod>> mods)
+        {
+            // TODO: find a more permanent solution for this if/when it is needed in other components.
+            // this is generating drawables for the only purpose of storing bindable references.
+            foreach (var r in references)
+                r.Dispose();
+
+            references.Clear();
+
+            ScheduledDelegate debounce = null;
+
+            foreach (var mod in mods.NewValue.OfType<IApplicableToDifficulty>())
+            {
+                foreach (var setting in mod.CreateSettingsControls().OfType<ISettingsItem>())
+                {
+                    setting.SettingChanged += () =>
+                    {
+                        debounce?.Cancel();
+                        debounce = Scheduler.AddDelayed(updateStatistics, 100);
+                    };
+
+                    references.Add(setting);
+                }
+            }
+
+            updateStatistics();
         }
 
         private void updateStatistics()

osu.Game/Skinning/DefaultLegacySkin.cs

@@ -13,13 +13,12 @@ namespace osu.Game.Skinning
             : base(Info, storage, audioManager, string.Empty)
         {
             Configuration.CustomColours["SliderBall"] = new Color4(2, 170, 255, 255);
-            Configuration.ComboColours.AddRange(new[]
+            Configuration.AddComboColours(
-            {
                 new Color4(255, 192, 0, 255),
                 new Color4(0, 202, 0, 255),
                 new Color4(18, 124, 255, 255),
-                new Color4(242, 24, 57, 255),
+                new Color4(242, 24, 57, 255)
-            });
+            );
 
             Configuration.LegacyVersion = 2.0m;
         }

osu.Game/Skinning/DefaultSkin.cs

@@ -35,7 +35,7 @@ namespace osu.Game.Skinning
                     switch (global)
                     {
                         case GlobalSkinConfiguration.ComboColours:
-                            return SkinUtils.As<TValue>(new Bindable<List<Color4>>(Configuration.ComboColours));
+                            return SkinUtils.As<TValue>(new Bindable<IReadOnlyList<Color4>>(Configuration.ComboColours));
                     }
 
                     break;

osu.Game/Skinning/DefaultSkinConfiguration.cs

@@ -1,8 +1,6 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-using osuTK.Graphics;
-
 namespace osu.Game.Skinning
 {
     /// <summary>
@@ -10,15 +8,5 @@ namespace osu.Game.Skinning
     /// </summary>
     public class DefaultSkinConfiguration : SkinConfiguration
     {
-        public DefaultSkinConfiguration()
-        {
-            ComboColours.AddRange(new[]
-            {
-                new Color4(255, 192, 0, 255),
-                new Color4(0, 202, 0, 255),
-                new Color4(18, 124, 255, 255),
-                new Color4(242, 24, 57, 255),
-            });
-        }
     }
 }

osu.Game/Skinning/LegacyBeatmapSkin.cs

@@ -12,6 +12,8 @@ namespace osu.Game.Skinning
         public LegacyBeatmapSkin(BeatmapInfo beatmap, IResourceStore<byte[]> storage, AudioManager audioManager)
             : base(createSkinInfo(beatmap), new LegacySkinResourceStore<BeatmapSetFileInfo>(beatmap.BeatmapSet, storage), audioManager, beatmap.Path)
         {
+            // Disallow default colours fallback on beatmap skins to allow using parent skin combo colours. (via SkinProvidingContainer)
+            Configuration.AllowDefaultComboColoursFallback = false;
         }
 
         private static SkinInfo createSkinInfo(BeatmapInfo beatmap) =>

osu.Game/Skinning/LegacySkin.cs

@@ -72,7 +72,11 @@ namespace osu.Game.Skinning
                     switch (global)
                     {
                         case GlobalSkinConfiguration.ComboColours:
-                            return SkinUtils.As<TValue>(new Bindable<List<Color4>>(Configuration.ComboColours));
+                            var comboColours = Configuration.ComboColours;
+                            if (comboColours != null)
+                                return SkinUtils.As<TValue>(new Bindable<IReadOnlyList<Color4>>(comboColours));
+
+                            break;
                     }
 
                     break;

osu.Game/Skinning/LegacySkinConfiguration.cs

@@ -3,7 +3,7 @@
 
 namespace osu.Game.Skinning
 {
-    public class LegacySkinConfiguration : DefaultSkinConfiguration
+    public class LegacySkinConfiguration : SkinConfiguration
     {
         public const decimal LATEST_VERSION = 2.7m;
 

osu.Game/Skinning/SkinConfiguration.cs

@@ -14,7 +14,36 @@ namespace osu.Game.Skinning
     {
         public readonly SkinInfo SkinInfo = new SkinInfo();
 
-        public List<Color4> ComboColours { get; set; } = new List<Color4>();
+        /// <summary>
+        /// Whether to allow <see cref="DefaultComboColours"/> as a fallback list for when no combo colours are provided.
+        /// </summary>
+        internal bool AllowDefaultComboColoursFallback = true;
+
+        public static List<Color4> DefaultComboColours { get; } = new List<Color4>
+        {
+            new Color4(255, 192, 0, 255),
+            new Color4(0, 202, 0, 255),
+            new Color4(18, 124, 255, 255),
+            new Color4(242, 24, 57, 255),
+        };
+
+        private readonly List<Color4> comboColours = new List<Color4>();
+
+        public IReadOnlyList<Color4> ComboColours
+        {
+            get
+            {
+                if (comboColours.Count > 0)
+                    return comboColours;
+
+                if (AllowDefaultComboColoursFallback)
+                    return DefaultComboColours;
+
+                return null;
+            }
+        }
+
+        public void AddComboColours(params Color4[] colours) => comboColours.AddRange(colours);
 
         public Dictionary<string, Color4> CustomColours { get; set; } = new Dictionary<string, Color4>();
 

osu.Game/Updater/UpdateManager.cs

@@ -11,7 +11,10 @@ using osu.Game.Overlays.Notifications;
 
 namespace osu.Game.Updater
 {
-    public abstract class UpdateManager : CompositeDrawable
+    /// <summary>
+    /// An update manager which only shows notifications after an update completes.
+    /// </summary>
+    public class UpdateManager : CompositeDrawable
     {
         [Resolved]
         private OsuConfigManager config { get; set; }

osu.Game/osu.Game.csproj

@@ -23,7 +23,7 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite.Core" Version="2.2.6" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
     <PackageReference Include="ppy.osu.Game.Resources" Version="2019.1215.0" />
-    <PackageReference Include="ppy.osu.Framework" Version="2019.1215.0" />
+    <PackageReference Include="ppy.osu.Framework" Version="2019.1225.0" />
     <PackageReference Include="Sentry" Version="1.2.0" />
     <PackageReference Include="SharpCompress" Version="0.24.0" />
     <PackageReference Include="NUnit" Version="3.12.0" />

osu.iOS.props

@@ -74,7 +74,7 @@
   </ItemGroup>
   <ItemGroup Label="Package References">
     <PackageReference Include="ppy.osu.Game.Resources" Version="2019.1215.0" />
-    <PackageReference Include="ppy.osu.Framework.iOS" Version="2019.1215.0" />
+    <PackageReference Include="ppy.osu.Framework.iOS" Version="2019.1225.0" />
   </ItemGroup>
   <!-- Xamarin.iOS does not automatically handle transitive dependencies from NuGet packages. -->
   <ItemGroup Label="Transitive Dependencies">
@@ -82,7 +82,7 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="2.2.6" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite.Core" Version="2.2.6" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
-    <PackageReference Include="ppy.osu.Framework" Version="2019.1215.0" />
+    <PackageReference Include="ppy.osu.Framework" Version="2019.1225.0" />
     <PackageReference Include="SharpCompress" Version="0.24.0" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="SharpRaven" Version="2.4.0" />

osu.iOS/Application.cs

@@ -5,7 +5,7 @@ using UIKit;
 
 namespace osu.iOS
 {
-    public class Application
+    public static class Application
     {
         public static void Main(string[] args)
         {

osu.iOS/OsuGameIOS.cs

@@ -4,11 +4,19 @@
 using System;
 using Foundation;
 using osu.Game;
+using osu.Game.Updater;
 
 namespace osu.iOS
 {
     public class OsuGameIOS : OsuGame
     {
         public override Version AssemblyVersion => new Version(NSBundle.MainBundle.InfoDictionary["CFBundleVersion"].ToString());
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            Add(new UpdateManager());
+        }
     }
 }