As promised, a quick prototype for Guitar Zero: a cheerfully silly (and surprisingly mechanically intensive) match-3 game.
You’re performing for a crowd that doesn’t expect much of you. Find matches in the shape of power chords, and you’ll build up your multiplier–but also the fans’ expectations. Disappoint them too many times when they’re getting excited, and they’ll boo you off the stage! Get enough points before you’ve played fifty chords/made fifty matches to win.
Guitar Zero is a test of how one might keep players challenging themselves as their skill level increases. You can reach the end with little difficulty–but you won’t win that way. Succeeding requires taking on some risk. To get a truly great score, you’ll need to put yourself to the test.
The Law of Game Design 