Finally finished this after several days of torturing over the puzzles. I normally don't go for math puzzles as they make me feel dumb but this was a really beautiful game so I had to give it a go.
The puzzles certainly scale in difficulty, and I had to refer to the walkthrough on two occasions to find a correct starting position. I think the game might benefit from tips on how you should look to solve these kinds of puzzles as I haven't really come across this before. I often found myself doing some scratching-the-surface level thinking about the puzzle before just attempting to colour change as much as possible! So sometimes the game felt, for me, more trial and error than the thinking I really wanted to do.
Beautiful game though, good calm music, and a joy to play - didn't overstay its welcome either. Congrats!