First of all, you should not have used MMF2 to make this game.
Disregarding the awful engine, the level design is very bland and empty. The aesthetics are boring.
Your boss is also pretty boring, after the donut it just stands there until you kill it. You should have it loop attacks.
And how come I can only fire 2 bullets at once? That's annoying.
I'm not sure if those boshy attacks are there as a joke or not but I would suggest removing them. I'm not sure why you even released this game since this demo is so short.
My advice: Start over, and this time use a game maker engine.