Description

Tic tac toe game in which two players alternately put  crosses and circles in one of the compartments of a square grid of nine spaces; the object is to get a row of three crosses or three circles before the opponent does.

Game Rules

1. There are two players; one plays with the X sign and the other one plays with the 0 sign.
2. They both move alternately, starting with the X player.
3. They can move only in empty squares.
4. Initially, the board is made of 9 empty squares, aligned on a 3x3 board.
5. The purpose of the game is to make 3 own signs on a column, row or diagonal.
6. If the board is filled but none of the players managed to achieve this goal, then the game ends in a draw.
   

Strategy

1. Win: If the player has two in a row, they can place a third to get three in a row.
2. Block: If the opponent has two in a row, the player must play the third themselves to block the opponent.
3. Fork: Create an opportunity where the player has two ways to win (two non-blocked lines of 2).
4. Center: A player marks the center. (If it is the first move of the game, playing on a corner gives the second player more opportunities to make a mistake and may therefore be the better choice; however, it makes no difference between perfect players.)
5. Opposite corner: If the opponent is in the corner, the player plays the opposite corner.
6. Empty corner: The player plays in a corner square.
7. Empty side: The player plays in a middle square on any of the 4 sides.