Ultimate Tic-Tac-Toe

Ultimate Tic-Tac-Toe is similar to regular tic-tac-toe, except there's a smaller game inside each of the larger boards. The goal, as always, is to win 3 in a row on the global board. The local square a player picks reflects the location on the global board that the other player must move to on their next turn.

Two player only, but if you really want a one-player challenge, try to fill up every single space without capturing a large square.