The pixel art is very cute, and the music complements it well. We agree with the other commenters that having the camera focussed on the player would probably improve the experience, but an even bigger upgrade would be some kind of health bar for the enemy. This would allow the player more feedback on how well they are doing, which gives a sense of progress even if you lose (since you can compare how much damage you did vs the previous try). The boss having different phases was a nice touch that added to the challenge :)