Hello! Just played the game and found it amazing. Original, interesting, actually "skill-based" and founded on the imaginary of the great Escher. Very well done!
I just want to point out that I may have found a little "bug", or maybe exploit is the right word. When you have a cube picked up, while walking, if you drop the cube and then jump twice (in a fast sequence) you'll actually jump higher than just putting the cube on the ground and using it as a step. Probably because the second jump starts while the character is at the peak of the first one. By the way, I found this late in the game while playing "Meeting", so I don't know if it can be exploited to skip some levels, but I know that in "Run" you can use it to jump over the closed door without having to do the normal procedure.