Supercars was class, but if you rewrote it nowadays it would look just a little dated..

I think the RPG's the way to go to be honest. There are two games being written by people on these forums already; Sentience (a turn based 2d strategy game) and Times of War (a 3d real time strategy) so the strategy aspects are already pretty well covered.

Yep, RPG's the way to go - but you'll have to think of something that sets it aside from Myst, FFVII otherwise it's just going to look like their ugly half cousin....