Tic tac toe is a game where players take turns placing their mark on the board. The first to line up the required number of marks in a row — horizontally, vertically or diagonally — wins. On a 3×3 board you need 3 marks in a row; on 4×4, 5×5 and 6×6 boards you need 4 in a row. You can play against the computer, with a friend over an invite link, or against a random player online.