"Alternate Names" aka pseudo-prerequisites. E7 and MSLO can be built again.

OpenRa.Game/GameRules/TechTree.cs

@@ -25,7 +25,13 @@ namespace OpenRa.Game.GameRules
 		{
 			var ret = new Cache<string, List<Actor>>( x => new List<Actor>() );
 			foreach( var b in Game.world.Actors.Where( x => x.Owner == player && x.Info != null && x.Info.Traits.Contains<BuildingInfo>() ) )
+			{
 				ret[ b.Info.Name ].Add( b );
+				var buildable = b.Info.Traits.GetOrDefault<BuildableInfo>();
+				if( buildable != null )
+					foreach( var alt in buildable.AlternateName )
+						ret[ alt ].Add( b );
+			}
 			return ret;
 		}