Why can't I use my mx518 mouse with the game? It won't let me map anything to it. Any and all help would be greatly appreciated. Thanks.

FWIW I'm using an MX518 just fine with this game. I have no idea why it would cause issues for you.

What is meant, I believe, is that you can't map actions to the mouse buttons. For instance, I use Left mouse for Forward and Right mouse for Back in all of my FPSs. This game does not allow that mapping - at least from the options ui.

edit: Nevermind, I read the readme, which the OP should as well.