I agree with Bill--seems like you're relying pretty much on an honor system here! Even with a surprise element, there's no way of knowing if someone hasn't already gotten a Roguelike done and just needs to add in the element. The only way this would work would be for people to meet at a camp or some such where the environment could be carefully controlled.

That said, I like the idea of a roguelike contest. As you know, I entered the IF Comp last year and had a great time learning C++. I can't help but be tempted to now try my hand at a roguelike. Not going to happen this year, though! They really ought to do this kind of stuff in the summer, when people have more time.