Something i would like to see:

+intro (not necessarily an animation, but it should explain the main story in less then 2 minutes)
+1 level about 10 minutes minimum playtime (this would recommend balancing, a very important issue in st games)
+extro statistic (splashscreen including game stats like killed and lost units)

Everything till April 1st (6 months are a minimum for guys who can do this spare time based only).

Prize: This acutally sound like a teamwork job (because it has tons of stuff to care about).

I think 200bucks are way not enough for that much work but it still might be ok for eveybody else.