From the very first second the game opens (well even from the Itch page) it's easy to tell how much time you put into polishing everything, which culminates in the game being incredibly crisp and satisfying to play.
The art was good and consistent, the pacing was fantastic, the sound added the necessary punch and the music was fitting.
The only thing I had on my mind when playing was "why the mouse?" It felt as if the gameplay could have been even smoother if I was switching the zones with another key, as for the majority of the game it didn't matter so much which of the cubes you used to switch zones. That said, if you still wanted to keep it directional you could perhaps use the arrows. Not sure, would be interested to hear if you had a particular reason for using the mouse there.
But, really, such a great submission!