I'm assuming that it's way too much work and that all of the RPGM's engines aren't anywhere NEAR the power they need to be at for platforming. This is a program floating around this forum for making a platform game, specifically one that can be exported as either its natural game file, a flash game, or xbox live arcade game. I'm way too freakin' tired at the moment as I just woke up, to go and look for this for you, but I know it's a fairly recent topic in the Other Programs board or something.