Just bought a new xbox

[DirtyP2002]

Except the big ones (Forza, Fable, Halo, Gears) I recommend you

- Alan Wake
- Splinter Cell Conviction
- Geometry Wars 2
- Halo Wars
- Kameo
- Trials HD / Evolution

and if you are open-minded enough to try Kinect with a couple of friends:

- Dance Central
- Kinect Sports

Some very underrated games you should give a try. Most of them are very cheap these days.