Trait-based units. Any unit/building without sequences will cause a crash when built.

OpenRa.DataStructures/OpenRa.DataStructures.csproj

@@ -42,6 +42,7 @@
     <Compile Include="int2.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Tuple.cs" />
+    <Compile Include="TypeDictionary.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 

OpenRa.DataStructures/TypeDictionary.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace OpenRa
+{
+	public class TypeDictionary
+	{
+		Dictionary<Type, object> inner = new Dictionary<Type, object>();
+
+		public void Add<T>( T val )
+		{
+			inner.Add( typeof( T ), val );
+		}
+
+		public void Remove<T>()
+		{
+			inner.Remove( typeof( T ) );
+		}
+
+		public bool Contains<T>()
+		{
+			return inner.ContainsKey( typeof( T ) );
+		}
+
+		public T Get<T>()
+		{
+			return (T)inner[ typeof( T ) ];
+		}
+
+		public IEnumerable<T> WithInterface<T>()
+		{
+			foreach( var i in inner )
+				if( i.Value is T )
+					yield return (T)i.Value;
+		}
+	}
+}