I purchased this game around Christmas time on a Steam sale and I can't recommend it enough. It's a real trip, 70's style sci-fi, I even love the retro film grain effect and the gaudy 70's rainbow effects that happen when you accomplish certain goals.
The premise is that you are a disembodied head in a helmet, in a future run by robots. You "headland" on headless robotic bodies and attack other robots in locations you can't reach, you blast off their head so you can dismount and then attach to their body and continue through the maze to eventually reach the evil AI controlling the universe. The controls are dead simple, the graphics and music are beautiful, I'm really enjoying it.
http://www.adultswim.com/games/pc-console/headlander/