Geometry Wars
Bejeweled 2
Hexic HD

These games are just so addicting that you keep coming back for more and more (that's the sign of a good game, right?)

There are plenty of amazing 360 games in the works, but if you get a systme, make sure you hook it up online, and get these games....you won't regret it.

Update:

Just purchased Marble Blast Ultra, and I think this might be the best game of the lot. The single player game is addicting (getting better times, easter eggs, etc.) and the multiplayer is good fun as well. It's kind of like Marble Madness for NES, but updated....

Definitely an excellent addition to the Live Arcade.

Freakn A, I just recently went over to my friends house over spring break, and we brought his 360 downstairs to his, 'Dads' TV, and we hooked it up. But this isn't no ordinary TV, it was a 50inch Panasonic Plasma HDTV. 50 inch. We played a bit of Fight Night, DOA, Ghost Recon, Oblivion, and PGR. I had to check out the rest of his games, and I found geometry wars II. The improvements they made to the game makes it so much better to look at. I loved the way Bizzare added the Blue Grid as a background, and the effects they created when you drop bombs, or when you get thoes special missles. When shooting the missles, the neon blue grid turns into this gas looking substance and exhales through the map. It looks like the missles create blue coughs which billow out from your gunner. Totally cool effect, (which I didn't describe very well.) They also added the last thing to hit you when you die, so you can be curse obscenities and swear that that, little pink box wasn't there when it hit you.