That's what I was going to say, if we want to create a game to win a prize, I think that the best way to do this is to create a game to sell it to players.
In my opinion, winning a prize in a Game Jam is just a bonus, but the first prize is to have the opportunity to make a game, to be proud of what you've done and to learn a lot. Having some new contacts, having fun (even if it's not always funny to spend time to do something which is not working / not as you thought).
Having prizes "Unity-oriented" is not something which is bad for me, they wants to create an event, Unity replied that they were gonna support it, it's just a good thing.
You can't have a prize which is going to be really cool for everyone, a pixel editor software licence ? What if I'm making 3D games without any pixel art ? A game engine licence ? What if I don't want to use it or if I've already got this licence ? etc.
Just be proud of what you're doing, Maybe you'll be good enough to win a prize, then if you don't want to use it, try to find a friend or someone who needs it, you'll make someone's day. :)
Have fun /all ! :D