Wednesday, September 4, 2019

Ultimate Tic Tac Toe

If you think classic Tic Tac Toe is too easy for you - try Ultimate Tic Tac Toe! This game (also known as Strategic Tic Tac Toe or Super Tic Tac Toe) is much more complex - there is no known strategy or algorithm to win (or even to draw) the game. But the game rules are still very simple, so everyone can enjoy it!

Ultimate Tic Tac Toe is played simultaneously on 9 classic Tic Tac Toe boards (called local boards) arranged in a 3x3 grid (called the global board). So in total, there are 81 small squares available for the players. The arrangement is shown below. For illustration purposes, the local board in the upper left corner is highlighted in red and the local board in the center is highlighted in blue.


As in the classic Tic Tac Toe game, players take turns marking small squares on a local board with X’s and O’s respectively. To win a game, a player must win, by the classic Tic Tac Toe rules, three local boards in the same row, column or diagonal on the global board. The local boards won by the X-player are highlighted in blue and those won by the O-player are highlighted in red. In the picture below X-player wins the game by winning three local boards in the middle row of the global board.


What makes the game tricky and fun are the 4 rules dictating which of the 9 local boards is used for the next move. For assistance, the squares available for the next move are highlighted in green.

Rule #1: The X-player makes the first move and can choose any of the 9 local boards for it - so all 81 small squares are green at the beginning.


Rule #2: By marking a small square on a local board a player determines the local board that his/her opponent must use for their next move - this local board should have the same relative position on the global board as the marked square position on the local board. In the example below, X-player selected the top left corner on a local board. That means O-player must play on the top left local board.


Rule #3: If a player wins a classic Tic Tac Toe game on a local board, the board becomes complete and its small squares (even empty ones) cannot be used for subsequent moves. The local boards won by the X-Player are highlighted in blue and those won by the O-Player are highlighted in red. For example, the global board below shows one local board won by the X-Player, one by the O-player, and one tied.


Rule #4: If a local board that a player was sent to by rule #2 is already completed, the player can use any non-completed board. In the example below, the O-player marks the right middle square on the local board in the bottom left corner. By rule #2, the X-player must play on the right middle local board. But this board is already completed! So the X-player can play on any available local board.




That's it! This is a really fun game to play. I have just published a free android app for it. Check it out and enjoy the game!

Get it on Google Play

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