Now I think this should be set up and can actually go around and work! Now I'm all for the platform genre, because it's much easier to create loads of fancy effects and animations when not having to think too much about perspective (and topdown is boring!); though I guess isometric can work.
But basically you can set up a to do list and get the game up and running, and every temporary sprite in the game is probaly a brightly coloured block to display size and nothing but that; so if you have that, and post it here, together with all the sprites extracted form the game with a bit of description (but absolutely not too much!) and have everyone state which object they are going to make, it won't be too hard to get at least 75% done in a short while, the other 25% is probably stuff nobody wants to do combined with stuff somebody signed up for but never finished, so at that point the rules and reassignments kan kick in.