I'm not sure if this is even possible, but I've had an idea. Its kind of short, and I can't do it myself.
A western mod. I'm talking about cowboys with more advanced guns. With heroes such as Billy the kid and Jessy James.

It shouldn't be too difficult to do, since the graphics of shooting guns is there (obviously) the trick would be in that each guy could shoot multiple times.

Another added problem is that I don't think the ENTIRE americas are there? I'm not sure about this though, so I could be wrong.

Then again, a western mod would be an excellent idea for an expansion