This was the last game I tried in this jam, and I must say thank you sir for ending my tests with such beauty.
I really liked your concept and enjoyed alot the minimalistic graphics and the cool background sound+sfx , its rare to see such complete game in a jam + you had so many levels to offer ( some were really hard man btw xD ) . the only thing that bothered me was that I couldn't jump to the next level when I finished one and had to go back to the menu everytime ( did I miss something or it was meant to be that way ? )
I also have a suggestion that will help you improve the juice in your game, that shadow effect that the player leaves behind him, it gets too far away sometimes making it unpleasing to see, I think you can add more shadows with less opacity by calculating an interpolation between last position and new position ( x+previous_x/2 , y+previous_y/2) for example
Great idea, and well executed, totally deserved the 5 stars!