Uhm, to create something? For challenge? For fun? That's what hackatons and gamejams are for, aren't they?

But I have to admit that sometimes there are pretty nice prices - like on the last gamejam I attended there was an organized trip to bigger gamejam for the winners (except of small stuff like T-shirts). There were no judges, all attendees voted on their favorites. That's in my opinion the true hackaton/gamejam spirit.