I'd certainly be willing to help on a Mario game, but I'm not sure if assigning worlds is the best approach. First of all, each person building the game would need the same program and the same engine and graphics and everything, or else the game would seem patched together. Secondly, even if the same code was used, it would be difficult to add things; it's almost impossible to understand another's code. Unless you meant the designing of individual worlds, which might work.
Still, it's a good idea, Marionut#1, of course it still needs to be planned/explained a bit more thouroughly..
Absorbed in the clouds, a voice from afar said
"With the right device you can make a pattern grow,
or you can tune up your car."