Mechanics
The jumping feels rewarding but sometimes the jump path disappears. Clicking isn't always responsive and can cause you to die because you need to be able to move quickly.
I love the arcade feel and look. The music and sound effects are superb. The boss was fun to fight and I didn't realize that you can kill the homing enemies until my 5th or 6th death. I think a small tutorial on beating the different enemy types would help them feel less like the game is cheating and feel more prepared to handle the boss.