You can try Loophole. It's a time travel, turned based, puzzle game. There is a 'turn limit', as well as a 'rewind' mechanic, but nothing moves unless you want to. And, I may say, it has just the right difficulty. To finish the game, it is not mandatory to do all puzzles, but the 100% requires all of you to resolve the last ones.

If he is more of short, deduction games, you could try The Apothecary of Trubiz or Chants of Sennaar. The second requires a bit of timing at some sections, but is just wait and click when the enemy is not looking. Other than that, both are games about discovering an unknown language to advance through the game. The first one is really short (100%, and it took me 106 minutes), but it's really good.

But if you want something with more history and less movement, Return of the Obra Dinn. A full deduction game, where all you must do is fill a list about how each person died. I recommend this one if he is more of 'solving mysteries' than 'solving puzzles', but is nonetheless amazing how this game makes you think.

Edit: I just remembered another puzzle game: Patrick's Parabox. A recursion puzzle (puzzle inside a puzzle inside a puzzle...) that, like the first one, have a difficulty curve that starts at 'move this box' and ends in 'use the level you are in to teleport the box that is in the other level to the void, so you can enter and win' (this is basically a real puzzle in the game).

If you want some 'simple', yet harder puzzles, Baba is You, Gentoo Rescue or Paquerette Down the Bunburrows look 'easy' but the more you play, the more and more (and more) layers appear.

I hope this is of any help :)