Sanctum

[super77]

Hey, if you guys haven't tried this already, it's a great Tower Defense/FPS game that has been out for a while. It has single player and co-op. It's a lot of fun with friends. I think there is also a demo to try. :)

Sanctum on Steam (http://store.steampowered.com/app/91600/)

[Grassman7z7]

Been playing it with a few buddies. It is a ton of fun, I definitely recommend it. Haven't done much single player, but who really likes playing with themselves hm?