ZP2k9 is a community game available on XBox Live Arcade, and frankly its pretty awesome for the small amount of money it costs (200pts). If you are familiar with Soldat, you'll understand what ZP2k9 is like. Its a sidescrolling shooter, with dual analog controls and awesome multiplayer and singleplayer play.

More info:

http://catalog.xna.com/en-US/GameDet...71469e7&type=2

As cheap as it is, its a steal. Check out the demo.