You should try Puzzles and Dragons. It's a puzzle game like that, but it adds in like...stats and RPG elements and stuff. It makes for a more complex and personal experience.

[He'll open the app and show her and bla bla bla.]

It makes there incentive to play beyond just beating the latest stage and getting the best score, or whatever...[And incredibly kindly, he'll offer the phone into her hands for her to try it out.]