My first question is:
Who actually owns the rights to sell it?
Without a collaboration agreement, work for hire agreement, or rights assignment, then NOBODY has the right to sell the final work. Legally each part is owned individually by each contributor. The transaction itself violates the rights of almost everyone who worked on the project.
Another way to pose this question would be around a band, who wrote a song, and go play at gigs. They receive money for playing, but how many bands (that don't start corporately funded) sign legal agreements with each other about ownership, funds distribution, etc..., unless it gets signed by a label. No band I've ever been in, or worked with.
True, no one would individually have the rights to sell the song that they all made together, but they would all agree to let it be played on the radio, or get paid to play it somewhere. It doesn't matter if all their amps and equipment belongs to one member alone. They still all get paid for it.
The group still makes the agreement together to have the game online and split the funds however.
So long statement short, The group as a whole has the rights to sell/decide how to proceed with it.