Wonderful story and a solid gameplay loop. I like the decision to progress through levels and have the final outcome depend on your overall success. It forces the player to try and think about each shot rather than just brute force trial and error each level.
I managed to get level 1 and 3 but could never finish level 2, I had maybe 5 attempts at it :P
A good amount of challenge, good use of physics and a wonderful little story. Nice work!