Wow, what a game! Very impressive what you did in this jam: Beautiful graphics, amazing sound, challenging and innovative game mechanics and very cool level design.
The only thing I would improve are the controls. I would have prefered [UP ARROW] for jumping and for example [SPACE] for the mirror effect. I think this is a bit more intuitive (or maybe just personal taste). However, when you design a game with [Z] as a control, always keep in mind that there are some QWERTZ keyboards out there :). It was possible to play but added an additional level of complexity for me :D.