it could be a really fun game
artists submitting should be free to put in as much or as little as they want,
want to just do a minion? cool, a couple of minions? a sub-boss, boss, player character and backgrounds? even cooler.
Or you could wait till certain art is approved and add to that specific artist's style. anything should go,
definitely need a programmer first to hammer out the mechanics and details, then let the artists loose on those mechanics , and be creative as possible within those limitations.