Pretty cool little game.
The visuals and the feel are really good. The camera is a bit strange but you can get used to it. I would have focused more on a single gameplay mechanic and make it as interesting and as deep as possible, also forcing the player to learn it through level design. I just feel like a lot of what you did is a bit redundant and doesn't really add much to the whole experience, and you could have spent more time polishing the melee attack (which is definetly the most fun and interesting), the waves and the enemy design.
Overall though, it's pretty enjoyable.