Male NoFail use an applicable interface

osu.Game/Rulesets/Mods/IApplicableFailOverride.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
+
+namespace osu.Game.Rulesets.Mods
+{
+    /// <summary>
+    /// Represents a mod which can override (and block) a fail.
+    /// </summary>
+    public interface IApplicableFailOverride : IApplicableMod
+    {
+        /// <summary>
+        /// Whether we should allow failing at the current point in time.
+        /// </summary>
+        bool AllowFail { get; }
+    }
+}

osu.Game/Rulesets/Mods/Mod.cs

@@ -55,10 +55,5 @@ namespace osu.Game.Rulesets.Mods
         /// The mods this mod cannot be enabled with.
         /// </summary>
         public virtual Type[] IncompatibleMods => new Type[] { };
-
-        /// <summary>
-        /// Whether we should allow failing at the current point in time.
-        /// </summary>
-        public virtual bool AllowFail => true;
     }
 }

osu.Game/Rulesets/Mods/ModNoFail.cs

@@ -6,7 +6,7 @@ using osu.Game.Graphics;
 
 namespace osu.Game.Rulesets.Mods
 {
-    public abstract class ModNoFail : Mod
+    public abstract class ModNoFail : Mod, IApplicableFailOverride
     {
         public override string Name => "NoFail";
         public override string ShortenedName => "NF";
@@ -20,6 +20,6 @@ namespace osu.Game.Rulesets.Mods
         /// <summary>
         /// We never fail, 'yo.
         /// </summary>
-        public override bool AllowFail => false;
+        public bool AllowFail => false;
     }
-}
+}

osu.Game/Screens/Play/Player.cs

@@ -298,7 +298,7 @@ namespace osu.Game.Screens.Play
 
         private bool onFail()
         {
-            if (Beatmap.Value.Mods.Value.Any(m => !m.AllowFail))
+            if (Beatmap.Value.Mods.Value.OfType<IApplicableFailOverride>().Any(m => !m.AllowFail))
                 return false;
 
             decoupledClock.Stop();

osu.Game/osu.Game.csproj

@@ -310,6 +310,7 @@
     <Compile Include="Overlays\Profile\Sections\Ranks\DrawableTotalScore.cs" />
     <Compile Include="Overlays\Profile\Sections\Ranks\ScoreModsContainer.cs" />
     <Compile Include="Overlays\Settings\Sections\Maintenance\DeleteAllBeatmapsDialog.cs" />
+    <Compile Include="Rulesets\Mods\IApplicableFailOverride.cs" />
     <Compile Include="Rulesets\Mods\IApplicableMod.cs" />
     <Compile Include="Rulesets\Mods\IApplicableToDrawableHitObject.cs" />
     <Compile Include="Screens\Select\ImportFromStablePopup.cs" />