You know, I'm also a member from BlenderArtist.org, where there is also a section about game making, normally threads like this one don't work out if there is no strong team leader.
As a recommendation I would make a list of game proposal (what genre, what kind of graphics/style, etc.) and a desired fixed minimum number of members with clear roles to do (graphics, code, sound, etc), then vote what to do and on that decision do brainstorms, when things are too open it's very hard to decide when to stop the brainstorm and "start working".