Love the idea of switching between two completely opposite worlds and it's done very well. Art also works really well. I like the idea of being able to switch to any level from the main menu, it makes a game of this genre, which often sees people getting stuck at one part, the accessibility to continue on. Maybe a next level button in addition to the main menu button on completion of a level would be helpful. The beginning few levels were maybe a bit too easy and movement could be a bit faster but that's about as far as my complaints go.
Overall, a really enjoyable play. Good job and good luck with the jam results! :)