Ultimate Tic-Tac-Toe: 9 boards of tic-tac-toe
Tic-tac-toe gets an extra floor: nine small boards inside a big one, and every move decides where your opponent plays next. Face the computer or challenge a friend on the same phone.
Your turn (X) · play on any open board
The blue boards are where you can play. Who starts alternates each game.
How to play Ultimate Tic-Tac-Toe
The big board has 9 small tic-tac-toe boards. Winning a small board (by getting three in a row on it) claims that square of the big board, and whoever wins three big squares in a row wins the game.
The golden rule: the square you mark sends your opponent to the board in the same position. Did you mark the top-right square of a small board? The next player must play on the top-right small board. The boards where you can play are highlighted in blue.
If you are sent to a board that is already won or full, you can play on any open board. Full boards without a winner count for nobody; if no player makes a big line, the game is a draw.
Frequently asked questions
Why is Ultimate Tic-Tac-Toe harder than regular tic-tac-toe?
Because every move has two effects: it may help (or not) on the small board and it chooses where the opponent plays next. Sometimes it is worth giving up a small chance so you do not send the other player to a board where they win.
How does the computer choose its moves?
It uses Monte Carlo Tree Search: it simulates thousands of random games from each possible move and chooses the one that wins most often. On the easy level it simulates little; on the hard level, much more, and it plays quite cleverly.
Any tips for winning Ultimate Tic-Tac-Toe?
Avoid sending your opponent to boards where they already have two in a row, and watch the center: the middle board is part of many big lines. Sending the other player to a board that is already decided gives them a free move, which is usually a gift.