I really enjoyed your game, one of the best I've played so far!. Playability is really smooth and the levels are very well done. I would change the fact that you can go through the "canon tiles" (I think third or four puzzle made you realise that you can do this and I found it very confusing). Also, you could add some canons which fire bullets at a diferent speed rate (every two tiles),to add a new dimension. But even without this suggestions the game is great and it has room for a lot of combinations for future puzzles. Congrats!