Make a RulesetDatabase.

osu.Game/Database/RulesetInfo.cs

@@ -0,0 +1,24 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using osu.Game.Modes;
+using SQLite.Net.Attributes;
+
+namespace osu.Game.Database
+{
+    public class RulesetInfo
+    {
+        [PrimaryKey, AutoIncrement]
+        public int ID { get; set; }
+
+        public string Name { get; set; }
+
+        public string InstantiationInfo { get; set; }
+
+        [Indexed]
+        public bool Available { get; set; }
+
+        public Ruleset CreateInstance() => (Ruleset)Activator.CreateInstance(Type.GetType(InstantiationInfo));
+    }
+}