Almost anyone knows how to play tic-tac-toe, but not everyone knows the strategy that guarantees they'll never lose another game.
Almost anyone knows how to play tic-tac-toe, but not everyone knows the strategy that guarantees they'll never lose another game.

Draw your tic-tac-toe board on a piece of paper using a pen or pencil. It should have nine squares total, with three on the top, three in the middle, and three on the bottom.
Whether you are flipping a coin or throwing dice, you need to win the right to the first move if you don't want to lose the game.
Mark the center square with an "X" or an "O." This is the key to guaranteeing you'll never lose in tic-tac-toe when you have the first move.
Following this rule will not guarantee you a win. It will guarantee that, even against a tic-tac-toe master, you will never lose.
After your opponent makes their mark, look to see if there is a square to the right of it available. If so, take it with your next move.
If the square to the right isn't available, take the square to the left with your next move.
If the squares to the right and left are taken, place your next mark above their last mark.
If the squares to the right and left and above your opponent's last move are taken, choose the square below it.
Repeat the right-left-above-and-below rule for each move you play. Congratulations! You may not win, but you'll never be a loser.
In the movie "WarGames," war is averted when the computer is shown that nuclear war, like tic-tac-toe, can not be won.