Top down puzzle. Arrow keys move, X undoes your moves, and Z is the confirm button for menus. The goal is to move over every tile without moving onto the same tile twice; a fairly common puzzle-type, and sure enough, a lot of the early levels are pretty boring and easy. That said, the game does start to get more challenging as the game progresses, and sure, part of that is because each world introduces new gimmicks and you’ll start to have trouble keeping up with all of them, but there were also quite a few levels where I did remember what everything did and yet still had to think about how to solve the level for a couple minutes or so. Some of the levels near the end are larger than what the screen shows, which is always annoying since you have to burn an attempt simply to scout ahead, but at least there are only a few of them.
Plus, the game’s free, so I can definitely recommend it. There’s also a paid, non-mini version, but looking at its screenshots, the only thing that stands out to me is that it has more gimmicks, including a darkness gimmick of all things, so this free version might ironically be the better game by virtue of keeping its scope somewhat limited in comparison.