Hmm, this is interesting. The implementation of world-switching in this almost feels like a toned-down Eversion, especially the change in palette. I really liked the change of the character's sprite!
The switch is quite slow. Gameplay could be more dynamic if the change was a second slower.
Strangely enough, the light world didn't seem to have any purpose in the last two levels.
Good work! Congratulations on your first jam!