Thanks and glad you had fun with it(sorry if I made you angry at the screen :p) .
actually parallax scrolling brought some issues up which I didn't have enough time to address so I went for the easy answer lol, but you are absolutely right about that .
And yes I intended the explosion to have effect on the player but sometimes after the enemies die the explosion moves a bit and this was definitely not intended lol.
Also just fixed the quit button, thank you for that.
And for the difficulty issue, I would make it a bit easier but I don't thing changing the main stuff in game level would fall under polishing.
Thank you for playing.