Ultimate Tic-Tac-Toe
This site is an interactive Ultimate Tic-Tac-Toe (nine-board meta tic-tac-toe) game with AI, online play, puzzles, openings, and analysis. Enable JavaScript to play.
Rules in short: nine small 3×3 boards form one large meta-board; your local square sends the opponent to the matching meta-board; win three small boards in a row on the meta-grid to win the match.