Main problem is that you don't feel when you've been hit, would be good if character have got some impact. And make fire rate faster. And controls are not convenient, it would be better use mouse to choose the direction. Boss is has too much hp. Also character could be more faster to give player more control in playing.
I know some people take criticism personal, but i do not try to smear dirt your work, i just give some advices if you want to continue your work in gamedev.