I'm going to have to say Halo 3, because of the impression the Halo 2 Live multiplayer left on me. I'm--along with hundreds of thousands of others--still playing it on Live. 😱
I'd have to say Prey comes next, along with Gears of War. They both look kickass. Overall, the 360 is totally going to rock the FPS world. 😎
And anyway, even though it hasn't yet been confirmed for the 360, how about Project Offset? I'm looking forward to that, also! 👆
Here's a thread made by Mist for Offset:
Release date isn't until 2007, but still... droolio