Uhh, I have two bog standard wired USB xbox controllers plugged into my PC. I can't control the game -- unless i make BOTH joysticks do the same thing at the same time (!) Seems like a bug, yeah? :P
Does it work ok if you unplug one of them? The game tries to use whichever controller has detected input last. Perhaps the deadzone on one of them is a bit off, which causes it two switch between controllers?
