Interest idea of a platformer you've got there! I enjoyed it quite a bit! The swapping between light and dark and the downward shoot as jump really make the game quite unique and standout. The game is obviously difficult but the general experience is quite good when you finally got the hang of it.
My little bit of complaint was that the enemies attack was way too fast, and dodging them seems really came down to chance than anything, also why shooting through walls? Another thing is that the fall damage is quite harsh in the sense that you can reach terminal velocity quite quickly, to the point where you can die in the witch's room via fall damage. I would suggest making the gravity a bit smaller and also a higher terminal velocity just to let the player some time to react.
But anyway, the game is quite well done, so good job!