I think it would be a good idea to make a game where you have to avoid the creeper heads bouncing around the screen by using the arrow keys to move your steve head (which is what's avoiding the creeper heads) for as long as possible. Use a timer in it so that you can get 1 score every 1 second. If you get hit by a creeper head then you lose and the scripts all stop. Then do a high score leader-board in the notes and credits section for the highest scores people have had! Silphaer's competition: http://scratch.mit.edu/discuss/topic/22899/?page=1#post-206018

Instrument simulation