Really really cool puzzle game!
The sounds were super loud, and I don't think I heard any music, but later I noticed there were settings for those. Whatever!
I really liked that last puzzle. The whole game was really enjoyable.
One thing that I want to say, is give the player a bit more space to walk around. These one tile corridors on much larger scale puzzles was kind of annoying. I would suggest either reducing the sizes of long pipes, or making the player be able to walk at least on two tile wide corridors.
I liked the tutorial as well.