Ages ago (Grade 9?) Paul, and myself took the core rules of FASA's tabletop game Battletech and simplified it to the point where almost anyone with little to no gaming experience can pick it up and play.
After some digging and some work we managed to put those rules online at battletech.sdf1.net in wiki form. If you care to look, feel free, even make comments. If you wish to help flesh out the rules, all the better! Of course you can just use the rules and start up your own game.