TicTacToe

Tic-tac-toe (American English), noughts and crosses (British English), or Xs and Os is a paper-and-pencil game for two players, X and O, who take turns marking the spaces in a 3×3 grid.

The player who succeeds in placing three of their marks in a horizontal, vertical, or diagonal row wins the game.

Players soon discover that the best play from both parties leads to a draw.

Hence, tic-tac-toe is most often played by young children, who often have not yet discovered the optimal strategy.