Really like the game - it was a bit hard to hit the ground turrets, but fun. Maybe a minimap might be a nice addition, or pointers on the edge of the screen that show you where the enemies are? Finding them was half the battle. Also, I would suggest reducing their trigger-radius - i.e. the distance that you are from them before they attack - as I found that I was being destroyed when I couldn't even see them! Finally, I would put the attacks as keys on the keyboard as you don't need them on the mouse, seeing as the mouse position does not affect the direction of attack.