I like puzzle games, and this was pretty fun. The concept's good, and I liked that you expanded on it with space-time machines and multiple time machines at once. The level designs do get a bit complex, and I got stuck two or three times before finally finishing it. Honestly, with how long you can get stuck on a puzzle for, it's enough time that I would suggest queuing up a second or third music track so the player doesn't go insane, because the endless loop coupled with the high-pitched time machine noises make the game unpleasant to listen to if playing for more than a couple of minutes. Another suggestion I have is to add a level counter on the side, so the player feels some sense of progression as they go through the levels. One note though- on my laptop, the overall window of the game is a lot larger than the actual level map. It's not too much of a problem because I could still see the level, but it's a bit strange.