I made a programming puzzle game that got overwhelmingly positive reviews by the very few people who downloaded it: 42 five-star reviews over 45 total.

I think that anyone who likes hard puzzles and spending many hours/days to solve some levels will enjoy it.

Also, if one happens to be a programmer that struggles with recursion, I think the game might help with that regard, but being a programmer is not a requirement to play.

Website: https://www.kidori.com/games/recursive/

Appstore: https://apps.apple.com/app/id1550504475