Tic Tac Together is team-based recursive tic-tac-toe. When both teams try to claim the same square at the same time, they have to fight for it by playing a subgame. Or a subsubgame. Et cetera. It's surprisingly strategic. How much board control should you give up to secure a contested square?

I've heard good things about Sunderfolk but haven't played it myself. It has hex-grid tactical combat with co-op done via smartphone, so only the buyer of the game needs to share their screen.