diff --git a/osu.Game.Rulesets.Catch/CatchRuleset.cs b/osu.Game.Rulesets.Catch/CatchRuleset.cs
index b8a844cb86..063294f836 100644
--- a/osu.Game.Rulesets.Catch/CatchRuleset.cs
+++ b/osu.Game.Rulesets.Catch/CatchRuleset.cs
@@ -24,7 +24,7 @@
 
 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);
 
@@ -134,7 +134,7 @@ public override IEnumerable<Mod> GetModsFor(ModType type)
 
         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();
     }
diff --git a/osu.Game.Rulesets.Mania/ManiaRuleset.cs b/osu.Game.Rulesets.Mania/ManiaRuleset.cs
index bf630cf892..dc2485bfb0 100644
--- a/osu.Game.Rulesets.Mania/ManiaRuleset.cs
+++ b/osu.Game.Rulesets.Mania/ManiaRuleset.cs
@@ -31,7 +31,7 @@
 
 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);
 
@@ -178,7 +178,7 @@ public override IEnumerable<Mod> GetModsFor(ModType type)
 
         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();
 
diff --git a/osu.Game.Rulesets.Osu/OsuRuleset.cs b/osu.Game.Rulesets.Osu/OsuRuleset.cs
index 27af615935..cab1980dde 100644
--- a/osu.Game.Rulesets.Osu/OsuRuleset.cs
+++ b/osu.Game.Rulesets.Osu/OsuRuleset.cs
@@ -32,7 +32,7 @@
 
 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);
 
@@ -178,7 +178,7 @@ public override IEnumerable<Mod> GetModsFor(ModType type)
 
         public override ISkin CreateLegacySkinProvider(ISkinSource source) => new OsuLegacySkinTransformer(source);
 
-        public override int? LegacyID => 0;
+        public int LegacyID => 0;
 
         public override IConvertibleReplayFrame CreateConvertibleReplayFrame() => new OsuReplayFrame();
 
diff --git a/osu.Game.Rulesets.Taiko/TaikoRuleset.cs b/osu.Game.Rulesets.Taiko/TaikoRuleset.cs
index ca7ab30867..a4cfce0dcc 100644
--- a/osu.Game.Rulesets.Taiko/TaikoRuleset.cs
+++ b/osu.Game.Rulesets.Taiko/TaikoRuleset.cs
@@ -24,7 +24,7 @@
 
 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);
 
@@ -133,7 +133,7 @@ public override IEnumerable<Mod> GetModsFor(ModType type)
 
         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();
     }
diff --git a/osu.Game/Rulesets/ILegacyRuleset.cs b/osu.Game/Rulesets/ILegacyRuleset.cs
new file mode 100644
index 0000000000..06a85b5261
--- /dev/null
+++ b/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; }
+    }
+}
diff --git a/osu.Game/Rulesets/Ruleset.cs b/osu.Game/Rulesets/Ruleset.cs
index 7ad93379f0..21d96123f1 100644
--- a/osu.Game/Rulesets/Ruleset.cs
+++ b/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>
@@ -103,11 +103,6 @@ protected Ruleset()
         /// <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>
@@ -148,7 +143,6 @@ protected Ruleset()
             Name = Description,
             ShortName = ShortName,
             InstantiationInfo = GetType().AssemblyQualifiedName,
-            ID = LegacyID,
             Available = true
         };
     }
diff --git a/osu.Game/Rulesets/RulesetStore.cs b/osu.Game/Rulesets/RulesetStore.cs
index 5d0c5c7ccf..5d2a7df458 100644
--- a/osu.Game/Rulesets/RulesetStore.cs
+++ b/osu.Game/Rulesets/RulesetStore.cs
@@ -59,16 +59,21 @@ private void addMissingRulesets()
                 var instances = loadedAssemblies.Values.Select(r => (Ruleset)Activator.CreateInstance(r)).ToList();
 
                 //add all legacy modes in correct order
-                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)
+                    int legacyId = ((ILegacyRuleset)r).LegacyID;
+
+                    if (context.RulesetInfo.SingleOrDefault(rsi => rsi.ID == legacyId) == null)
+                    {
+                        r.RulesetInfo.ID = legacyId;
                         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);