I love the art and the animations! The attack sound was a bit harsh, but other than that the  sound effects and music were great, too. It would probably go a long way if the enemies were spawned in at a random point in their animation, because right now they are all in sync. Also I noticed that the enemies don't actually ever attack the tower, which it feels like they are supposed to. These are minor details however, and I think the game is pretty fun.