Nice little platformer with a straightforward mechanic! I like the monotone visuals which make the light effects really pop.
My critique would be that the movement felt a little too fast for me, and the jump also felt a bit floaty. There was potential to introduce a few more mechanics and flesh out the game but I suppose your intention was just a nice simple short story and game.
A nice addition would be ability to restart with a key press (like enter on pause screen) because I had to go to my mouse to click the restart button.
Probably a bug: If you die in the first room (where you become the shadow), you have to start over again from the first dialogue and turn yourself into shadow again.
Overall pretty cool game, fits the theme and but I wouldn't say it stood out as something out of the ordinary (in my opinion)