I thought I'd bring up War of Rights here, since it is actually a very interesting take on FPS games. It's essentially an American Civil War game that takes much historical accuracy into account. The game even has a chain of command system. I am actually looking forward to the game very much, as I've been waiting for a proper American Civil War game to be released. If anybody else wants to support it, they have a kickstarter up here:
Be sure to check it out, it looks like quite an interesting concept and write what you think about it.