Part logic, part guessing
I wish it was heavier on pure logic, but the majority of puzzles end up with some guesswork. I used a couple hints just because I was too lazy to work through all the permutations on certain levels. Instead of tapping undo a dozen times for each guess, it might be cool to just tag the board just before the guessing begins and then have a single “undo everything back to the tag” button. All in all, a really fun game that took about 4 hours to finish.