Introduce IsPlayable(...) and obsolete UserPlayable

osu.Game/Rulesets/Mods/ModUsage.cs

@@ -0,0 +1,26 @@
+// 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.Mods
+{
+    /// <summary>
+    /// The usage of this mod to determine its playability.
+    /// </summary>
+    public enum ModUsage
+    {
+        /// <summary>
+        /// In a solo gameplay session.
+        /// </summary>
+        Solo,
+
+        /// <summary>
+        /// In a multiplayer match, as a required mod.
+        /// </summary>
+        MultiplayerRequired,
+
+        /// <summary>
+        /// In a multiplayer match, as a "free" mod.
+        /// </summary>
+        MultiplayerFree,
+    }
+}