cool game! i liked the music and art style. Puzzles were interesting but quite challenging. I think maybe you can consider making one or two easy - some kind of 'tutorial' levels - so that people will not get frustrated about dying several times already on the first level. I mean for some people it might be a quite difficult from the beginning. Also, i think maybe colliders are a bit larger then needed? also, i think maybe it is pixel art is tricking my mind but i somehow expected that movement is according to some 'grid': like if i press button 2 times i pass distance equal to two cubes, but i think it is not exactly like this. once for me it looked like i can pass it but i died.
but that's just suggestions, not really a critics. so - good job!