I like your art style. I'm not a puzzle game person because I'm not very clever. Like a lot of other commenters, I got stuck on the third puzzle. That being said, without really telling the player I think you could have used you first two puzzles to force the player to have an all on and an all off solution. With out this you leave the player to assume I the instructions and I assumed you needed all the lights on. With the run time for the game being so short, it could have been better to pad the player with easy wins then to get stuck on the third level and give up.