They're really digging deep now - this week's Live Arcade release is asteroids. Yes, that Asteroids:

Save the earth from a deadly deluge of asteroids and re-experience the beloved arcade classics "Asteroids" and "Asteroids Deluxe" on Xbox LIVE Arcade. Players control a spaceship in an asteroid field and shoot to destroy asteroids and saucers, all while trying to avoid a costly collision. Complete with re-mastered HD visuals and the whiplash inducing high-speed "throttle monkey" mode, players will be hooked for hours! "Asteroids" and "Asteroids Deluxe" will be available worldwide as a joint download for 400 Microsoft Points and are rated E for Everyone by the ESRB.

If you ever find yourself "hooked for hours" on a game of Asteroids you should probably seek medical attention.