TicTacToe

Tic-tac-toe (also known as Noughts and crosses or X's and O's) 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 best play from both parties leads to a draw. Hence, Tic-tac-toe is most often played by young children