Also known as: 三目並べ, 3目並べ, ○×ゲーム
A two-player game where the objective is to create a line of X's or O's (depending on which letter each player is assigned) within a 3 x 3 grid. Both players strategically attempt to block the other from completing a line of letters.
A common joke is to play tic-tac-toe on a character's Forehead to emphasize how big it is.