Feels incredibly polished, absolutely amazing! Music is great, the character is cute, UI is perfect!
The only issue i had was orientation: Handling the camera and the cubes felt a bit buggy. Often when trying to handle it, i ended up diagonally shifted to somewhere and had to hit the F key (btw, great thing you included that one :)
I did not play all the levels, so i do not know if it is doable, but maybe you could assign each cube to a number from 1 to 9, and hitting that number key rotates the cube? Or any other way to make the controls less susceptible to be confusing. If i could concentrate on the level itself instead of on the controls, that would be perfect!