Nice! The level design and the concept is great! I also like the lighting effect!
Suggestions ->
- Many times, the spikes were out of the camera's view so I could not predict where the player would land. You can increase the speed of the camera to fix this issue.
- There is no visual cue to tell if the player is sneaking. You can maybe add a squashing animation to tell that the player is sneaking, this would be a nice detail.
- Add "coyote time" ... since the game is a platformer, I think it would be great to have coyote time. It would make the game slightly easier but I think it would be worth it.
- Player-to-player interaction. You can add a feature in which the white player can jump on top of black player and ride on it when the black player changes gravity. This would unlock lots of new possiblities for new level designs!
- The plain square player sprite can be improved with squash-stretch animations. You can also add particles for when the player dies.