Pretty good game, cool. Levels pretty good, It would be good if you would make the jump button W too, because I'm used to that, 2D platformer games have W as a jump input. Also, in some levels, I think two, when you fall out, the player dosen't die, and there's no pause menu. So you gotta quit the old fashion way, ALT + F4, or windows key then close window.
The credits scene, game over screen when you die. Is kinda too bright, because the whole game is like, darker, droomier. And then PEW bright white screen, that kinda hurts your eyes a bit. But it's a good game. Mostly you don't need to change anything.
P.S. I don't want to be mean, just saying my thoughts. :)