Alright, here's how I think we could divide the work for the prototype:
Player: we need to integrate the shooting code from another game into the Ballworld and fine tune the controls/feel.
Level Design/Art: we need someone to design a level and create the art. Platform positions need to be determined.
Platforms: we need to figure out how to use Dambuilder's platforms in our game.
Items/Enemies: we need to have two seperate things we can run into, ie. Critters. We need them to have different functions (adding or removing fun) and need to tune the generation (hopefully coming from both sides).
Misc. Art: we need sprites and perhaps a title screen. General artwork and feel.