you've only changed little things about the game but it's already been improved a lot!
however, some criticism I have for the red dragon boss though: its hard to avoid and predict where projectiles in the boss go since they fire off in random directions, and it's especially hard considering the billion other things happening that could kill you at once. it goes to a point where it just becomes a matter of whether or not you're fast enough to kill the boss before the projectiles kill you.
i dont think you should remove the projectiles altogether, because i think you can do a lot more stuff with it. maybe just not make is as random and a bit easier to predict.
also i found a bug in the same boss fight where you can clip through the sides of the screen by repeatedly throwing yourself into them
