@numair: I don't use my n900 much or play games on it..

- Bounce is a good showcase, albeit way too short if you actually wanna play it for real...
- Angry birds is a favorite here... but if you have the iphone\ipad, then it's much better to buy it from the AppStore. Cheaper and comes with 3x as many levels.

If you're into emulator, there's a bunch of console and yester-years computer emulator. That's N900's strength, in this category...