The prize is $50,000 and a job as a Doritos game consultant – whatever that is. Focus on the $50,000 and getting your game made. You don’t actually need to win to be lucky enough to see your game in the Xbox Live Arcade either as they’ll pick the best two and put those head to head.
It’s not clear whether Xbox Live users outside America will get to either download or play the games. Both Xbox and Doritos are global brands and it’ll be disappointing if they try and lock out the rest of the world fully from this competition – but also interesting as gamer tastes in Japan (and less so in Europe) are very different from American players.