I love the independently-developed Community Games on Xbox 360. Sure, there's always the silly programmer's test with crappy graphics but if you download and try each game on the service like I do, you're going to find quite a few gems. And one of these is Awesome Tank.
Basically, you drive your tank around an intersecting grid filled with powerups and other tanks that are trying to shoot you. Simple gameplay, reminiscent of the old Crossfire and its variants, but packed with enough challenge and fun to keep you trying to get just that little bit higher on the top score table. The game has multiplayer, features "awardments" which aren't quite Gamerscore Achievements but close (there's even a few secret achievements which I haven't figured out yet), and other cool things. And oh yeah, about those scores. You're looking at Number Four (!) on the global score list. Hey, well, I'm proud of it. See if you can top my best score of 18,255. But look out for XboxHornet (21,530), DeadlySinCom (23,305), and the unbelievable Dutch125 (38.125).