Underscore + lowercase all keys

osu.Game/IO/Serialization/Converters/TypedListConverter.cs

@@ -45,13 +45,13 @@ namespace osu.Game.IO.Serialization.Converters
             var obj = JObject.Load(reader);
 
             var lookupTable = new List<string>();
-            serializer.Populate(obj["LookupTable"].CreateReader(), lookupTable);
+            serializer.Populate(obj["lookup_table"].CreateReader(), lookupTable);
 
-            foreach (var tok in obj["Items"])
+            foreach (var tok in obj["items"])
             {
                 var itemReader = tok.CreateReader();
 
-                var typeName = lookupTable[(int)tok["Type"]];
+                var typeName = lookupTable[(int)tok["type"]];
                 var instance = (T)Activator.CreateInstance(Type.GetType(typeName));
                 serializer.Populate(itemReader, instance);
 
@@ -84,16 +84,16 @@ namespace osu.Game.IO.Serialization.Converters
                 }
 
                 var itemObject = JObject.FromObject(item, serializer);
-                itemObject.AddFirst(new JProperty("Type", typeId));
+                itemObject.AddFirst(new JProperty("type", typeId));
                 objects.Add(itemObject);
             }
 
             writer.WriteStartObject();
 
-            writer.WritePropertyName("LookupTable");
+            writer.WritePropertyName("lookup_table");
             serializer.Serialize(writer, lookupTable);
 
-            writer.WritePropertyName("Items");
+            writer.WritePropertyName("items");
             serializer.Serialize(writer, objects);
 
             writer.WriteEndObject();

osu.Game/IO/Serialization/Converters/Vector2Converter.cs

@@ -18,7 +18,7 @@ namespace osu.Game.IO.Serialization.Converters
         public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
         {
             var obj = JObject.Load(reader);
-            return new Vector2((float)obj["X"], (float)obj["Y"]);
+            return new Vector2((float)obj["x"], (float)obj["y"]);
         }
 
         public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
@@ -27,9 +27,9 @@ namespace osu.Game.IO.Serialization.Converters
 
             writer.WriteStartObject();
 
-            writer.WritePropertyName("X");
+            writer.WritePropertyName("x");
             writer.WriteValue(vector.X);
-            writer.WritePropertyName("Y");
+            writer.WritePropertyName("y");
             writer.WriteValue(vector.Y);
 
             writer.WriteEndObject();

osu.Game/IO/Serialization/IJsonSerializable.cs

@@ -30,7 +30,8 @@ namespace osu.Game.IO.Serialization
             Formatting = Formatting.Indented,
             ObjectCreationHandling = ObjectCreationHandling.Replace,
             DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate,
-            Converters = new JsonConverter[] { new Vector2Converter() }
+            Converters = new JsonConverter[] { new Vector2Converter() },
+            ContractResolver = new KeyContractResolver()
         };
     }
 }

osu.Game/IO/Serialization/KeyContractResolver.cs

@@ -0,0 +1,16 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using Humanizer;
+using Newtonsoft.Json.Serialization;
+
+namespace osu.Game.IO.Serialization
+{
+    public class KeyContractResolver : DefaultContractResolver
+    {
+        protected override string ResolvePropertyName(string propertyName)
+        {
+            return propertyName.Underscore();
+        }
+    }
+}

osu.Game/osu.Game.csproj

@@ -272,6 +272,7 @@
     <Compile Include="Graphics\UserInterface\HoverClickSounds.cs" />
     <Compile Include="Graphics\UserInterface\HoverSounds.cs" />
     <Compile Include="Graphics\UserInterface\OsuButton.cs" />
+    <Compile Include="IO\Serialization\KeyContractResolver.cs" />
     <Compile Include="Migrations\20171019041408_InitialCreate.cs" />
     <Compile Include="Migrations\20171019041408_InitialCreate.Designer.cs">
       <DependentUpon>20171019041408_InitialCreate.cs</DependentUpon>