Pretty cool game, didn't expect to see so many levels. Kind of got stumped on level 6, so I'm glad there is a walkthrough video available. I've been playing the polished build, and one thing I was able to do is get the game stuck after pressing direction arrow and space as a cube falls. The next cube doesn't spawn so the level is stuck like that until I press Q. That's not really a big issue due to an easy way to get back to main menu, the players are probably not supposed to be able to suspend a cube midair.
The green cube's power wasn't very obvious, wouldn't have figured it out quickly if I hadn't seen how to use in the video.
Very impressive work overall, I had a lot of fun playing this!