We interrupt your current game-suggestion programming for this important XBLA-related news bulletin:
Attention all pinball fans! All three Pinball FX2 table packs - Marvel Pinball, Pinball FX1, and the Core Pack - are half-price starting today and running through next Tuesday! That's 400MSP for each pack of four tables, or 800MSP for the two packs worth getting (I've heard the FX1 tables are pretty bad, and would rather not spend the money to confirm such myself).
Attention all everything-else fans! A buttload of other games are on sale as well, including mega-hit Super Meat Boy (400MSP, a third of its regular price) and awesome racing game OutRun Online Arcade (400MSP - and note that this game will be pulled from XBLA at the end of the year due to Sega's Ferrari license expiring)! There will also be Black Friday and Cyber Monday single-day specials, so make sure to check in on those days!
Back on topic, we should play Gradius III (SNES). Unlike the arcade version, which you'll find a picture of next to the definition of "stupid hard" in the video game terminology dictionary I'm writing, the SNES version is so easy that most people here should be able to clear the first loop on a single credit on default settings within their first few tries, at which point they can learn how to play for score (which mainly consists of "kill things" and "don't die," but extended beyond the first loop).