Currently, I havent started my game, but with what I want to do would take to long to make. So do we have to make a "real" game with voice overs, story line and everything, or can it be like more of a  "sample" game where you just run around hacking and slashing enemies with AI? I was only wondering because I dont want to turn in a game that does'nt get jugded because a of a lack of story and such.

There's really no requirements for how full the game has to be. If it's fun, catches the judges interest for whatever reason (good gameplay, innovative, intriquing A.I., etc) that's the key to winning.

For the warmup, it's definitely a smart move to keep the game simpler and smaller in scope. Show off your creativity and clever A.I.. I don't speak for Microsoft or the contest judges however, so I don't know what just exactly is that special something they're looking for.

Either way, just get what you can done and have fun partiicpating!