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.
See also
Pixiv tag search: 三目並べ OR 3目並べ OR ○×ゲーム ("sanmoku narabe" or "maru-batsu game")
