Impressive level design. The "you lose what you use" platform mechanic is really cool, and you use it well. The puzzles are clever and unique, beatable without ragequitting, and the meaning of each type of platform is telegraphed well. Thanks for the controller support - that helped me reach the end, for sure. The background music was spookily chill, and fun to listen to.
This is fairly minor, but my biggest frustration was that sometimes I had to fully restart a level after wasting a double jump. I wish that the double-jumps were restored similar to how the platforms are restored, when the player is returned to a checkpoint. (I.e., if I reached the checkpoint with an unconsumed double-jump, I wish I got that double-jump power back; or if the double-jump item was on the map when I reached the checkpoint, it should be restored to the map when I'm reset to the checkpoint.) Hope that makes sense. That said, it wasn't hard to restart from the beginning of the map, just a little annoying to have to reach the checkpoint again.
Really fun game, I enjoyed it a lot!