It's a brilliant game! Excellent interpretation of the theme. I would have liked a little more evolution in the gameplay with a skill upgrade system or the addition of some kind of power-ups. Anything that could make me feel rewarded for my efforts. I think it could rebalance the gameplay and add a little more depth by offering a less linear progression, but overall the idea is really cool. Bravo!
Edit: A little background music could have been a nice addition too.