#115 New construction options

OpenRA.Game/GameRules/Rules.cs

@@ -55,5 +55,10 @@ namespace OpenRA
 			var y = files.Select(a => MiniYaml.FromFile(a)).Aggregate(MiniYaml.Merge);
 			return y.ToDictionary(kv => kv.Key.ToLowerInvariant(), kv => f(kv, y));
 		}
+
+		public static IEnumerable<string> Categories()
+		{
+			return Info.Values.Select( x => x.Category ).Distinct().Where( g => g != null ).ToList();
+		}
 	}
 }