Really cool idea and matches the theme perfectly! It's probably too hard for me, I only managed to finish the tutorial level after playing the other levels maybe 30 times without getting anywhere near the end of any of them. I would also agree with a lot of the feedback and give some more time between the player and shadow.
Maybe also shorten the death sequence since it's going to be happening a lot :D Found myself getting annoyed when I had to select the level again and again.
Overall really good game, good job! :D