I like the whole "Let's team up and create a game together!" idea.
In my opinion the best way to finish such a project is to set on simple but good and entertaining gameplay. Some people develop the gameplay and especially the movement in 1-3 weeks and spend a year on the rest. This is not the way to go.
A fresh multiplayer game would be great but (too) hard to create. The better option would be a 3d side scroller, I think, as mentioned above several times.
There should be more A7 side scrollers, too. Competition is good for business!