Only render units our race can build. That FACT prerequisite was unnecessary.

OpenRa.Game/Chrome.cs

@@ -532,6 +532,7 @@ namespace OpenRa.Game
 
 			var allItems = Rules.TechTree.AllItems(Game.LocalPlayer, queueName)
 				.Where(a => Rules.NewUnitInfo[a].Traits.Contains<BuildableInfo>())
+				.Where(a => Rules.NewUnitInfo[a].Traits.Get<BuildableInfo>().Owner.Contains(Game.LocalPlayer.Race))
 				.OrderBy(a => Rules.NewUnitInfo[a].Traits.Get<BuildableInfo>().TechLevel);
 
 			var queue = Game.LocalPlayer.PlayerActor.traits.Get<Traits.ProductionQueue>();

OpenRa.Game/GameRules/TechTree.cs

@@ -40,7 +40,7 @@ namespace OpenRa.Game.GameRules
 			var bi = info.Traits.GetOrDefault<BuildableInfo>();
 			if( bi == null ) return false;
 
-			if( !bi.Owner.Any( x => x == player.Race ) )
+			if( !bi.Owner.Contains( player.Race ) )
 				return false;
 
 			foreach( var p in bi.Prerequisites )

OpenRa.Game/SupportPower.cs

@@ -50,8 +50,7 @@ namespace OpenRa.Game
 				var buildings = Rules.TechTree.GatherBuildings(Owner);
 				var effectivePrereq = Info.Prerequisite
 					.Select( a => a.ToLowerInvariant() )
-					.Where( a => Rules.NewUnitInfo[a].Traits.Get<BuildableInfo>().Owner
+					.Where( a => Rules.NewUnitInfo[a].Traits.Get<BuildableInfo>().Owner.Contains( Owner.Race ));
-						.Any( r => r == Owner.Race ));
 
 				IsAvailable = Info.TechLevel > -1 
 					&& effectivePrereq.Any()

ra.yaml

@@ -1172,7 +1172,6 @@ POWR:
 	Buildable:
 		TechLevel: 1
 		Tab: Building
-		Prerequisites: fact
 		Owner: allies,soviet
 		Cost: 300
 		Description: Power Plant

rules.ini

@@ -1256,7 +1256,6 @@ Crewed=yes
 
 ; normal power plant
 [POWR]
-Prerequisite=fact
 Strength=400
 Armor=wood
 TechLevel=1