What a fantastic game. This is the types of submission I love, the ones that look like much but are really well designed.
The concept is simple enough but the levels show a great variety of situations. Playing it didn't feel boring because I was always challenges in different ways. The pacing of levels is also great. The difficulty is not always increasing, you might have a tough level followed by a few easier level. That's really great to keep getting engaged. Related to that, I am particularly fond of the levels that are identical but with just an element that change to raise the challenge or simple forces you to find a different solution. These are my favorites.
I also love that the levels have a main solution but still open to other one. The goal is simple, you just have to figure out how to achieve it, even if it means taking a detour, or cheesing it.
There is also some small details, like the sparkles of the goal that are always visible on the side even when it is out of the view. Nicely done.
My main complains is that there is too much level and that I couldn't finish it (because work!)
Amazing submission. I hope to see it on the GMTK recap video.