Initial commit: OpenRA game engine

Fork from OpenRA/OpenRA with one-click launch script (start-ra.cmd)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

OpenRA.Mods.Common/Traits/Replaceable.cs

@@ -0,0 +1,30 @@
+#region Copyright & License Information
+/*
+ * Copyright (c) The OpenRA Developers and Contributors
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System.Collections.Frozen;
+
+namespace OpenRA.Mods.Common.Traits
+{
+	public class ReplaceableInfo : ConditionalTraitInfo
+	{
+		[FieldLoader.Require]
+		[Desc("Replacement types this Replaceable actor accepts.")]
+		public readonly FrozenSet<string> Types = FrozenSet<string>.Empty;
+
+		public override object Create(ActorInitializer init) { return new Replaceable(this); }
+	}
+
+	public class Replaceable : ConditionalTrait<ReplaceableInfo>
+	{
+		public Replaceable(ReplaceableInfo info)
+			: base(info) { }
+	}
+}