I found this game incredibly easy as a programmer, but I know people from other fields had a hard time solving those puzzles.
If you’re actually looking for a challenge, look up Zachtronics' games. Especially the lesser known free games that don’t get as much recognition as the most popular ones (Spacechem or TIS). I myself felt in love with KOHCTPYKTOP (being an electronics nut helped, I should say).
I have shown it to my 13yo sister a few days ago and she appeared to like it.
Have you played it yet?
Played it, a dozen levels or so. Great game, funny, ironic (and at times, sad), and makes you think hard at times. The challenges of solving a puzzle within N steps, or X lines is particularly great. Also brings back old memories of Commodore BASIC.