WTF IS THIS????? Tanks and assault rifles in 1864 (during the American Civil War)!!!!
This was exactly my thoughts too. But that's what happens when every game developer is a sci-fi nerd. It's not "fun" or "exciting" unless it has mechs or aliens in it.
Don't get me wrong, I mean I'm in the process of creating a fantasy world for writing myself, so I enjoy creative things... But come on.
Best we could hope for, for a "proper" Civil War game might be a Mount and Blade total conversion...