Geometry Wars

Over Christmas I finally got a chance to play an Xbox 360 that was properly configured with giant HDTV, wireless controllers, good sound, and a few semi-tipsy friends to scream twitch-reflex color commentary. The best game by far was Geometry Wars. It's a simulated vector-graphics game with some modern GPU effects that costs only $4 over Xbox Live, and as Eric said, it looks like someone coded it up over the long Thanksgiving weekend. You could port this game to a graphing calculator and it would be just as playable. The spirit of Eugene Jarvis lives! (Sorry, Eugene, I know you're still alive.)