While working as the head coach at Google Code Next NYC, we had the kids complete a "runner" game and each coach made a quick sample project to give them idea... without giving them too many.
I made a quick fishies version where you are a underwater diver who has to avoid the fish which will get faster and change sizes as time goes on. It requires an Arduino to be played.
Suffice it to say... my game wasn't the least cool but my kids far surpassed this. They're pretty cool!
~ Caryn