Noughts and Crosses, Tic-tac-toe, Four-in-a-Row and Gomoku.Local and cross-platform WiFi multiplayer with or without AI. Single player campaign. Lots of variations in thousands of combinations, including misère, pie rule and disallowed overlines.
Exactly the kind of puzzle game I like (and will likely struggle to find someone to play against).
My instinct is I should have enjoyed it more than I did. I struggled to find the sweet spot for challenge vs fun. The default settings are just a plain memory game (on a small board). I fiddled with the settings pretty much at random and immediately found it too hard (I'm good at mental arithmetic - apparently less so once I need to also remember things).
Perhaps some kind of progression system which goes through different settings in some kind of approximate order of difficulty (or at lest some presets).