User blog comment:Bovell/Treyarch live stream interview/@comment-70.53.66.208-20100824130524/@comment-2254543-20100825005908

I posted this on another news article: They won't reveal because people like you and me are nearly losing our sanity trying to find out what the co-op mode is. That way, they can create more publicity so we can say 'wow, that makes this game seem awesome'. If they already revealed it, they would lose most of their would-be customers 2 months before the actual game's release.