oninego: Sorry for the late reply! We were all a bit tied up over the past few weeks with the Game Developers Conference and such. For future Game Design Challenges, feel free to get creative -- as long as you can justify your decisions in your design, then go for it!
On a related note, the results for this Game Design Challenge are now live!
More details here:
http://www.gamecareerguide.com/featu...me_design_.php