just for practice' sake, i'd love to make a 2.5D soldat clone. of course the programming would be easy, but such a small game would enable me to complete things like art assets to a satisfactory level without wasting tremendous amounts of time on the project.
i would LOVE to make a car game in future. one with lots of shader effects -- i find shader programming is heaps of fun and i'd enjoy seeing what i can do with them when i finish my HSC and get a few months off.
julz