Actually quite good game. I finished your game so I have few things to say. First of all shooting was pretty hard to understand, it took me a while, I suggest doing some kind of tutorial, not just writing controls. Secondly, enemies were very fast, also it was very annoying to die just from one bullet. The last suggestion would be to make boss level somehow more intuitive, because I was walking like 2-3 minutes around the room, until I understood what should I do :D  Overall great job, I really liked pixel art style, also music was cool too, game feels good and I enjoyed it!

Edit: Also I'm not a fan of shooting being locked in only 8 position.