I’ve gotten addicted to Bonza and Bonza Planet, which are 2 games made by the same developer that are, for whatever reason, 99% identical.
They are sort of like playing Scrabble in reverse. Take a finished Scrabble game, chop the finished rows and columns of words up into bite-sized pieces and then try to remake the layout by putting the words back together in their original rows and columns. If that’s not a good description, you can get a better idea by looking at the app pages.
They are freemium games, but come with a nice-sized collection of free puzzles (a couple hundred, maybe? It’s been too long to remember.) You also get a free puzzle every day with each app, so that’s actually 2 free puzzles a day, plus the plain Bonza app has like a 5-most-popular puzzles freebie every week. The puzzles are user-created and they get curated by the developers. You can play an unlimited (I think) number of the puzzles that haven’t been curated yet, they just might really suck or be really offensive.
Anyway between the 2 of them, good for up to 10 minutes a day while you’re waiting in line someplace.