We probably played our first Tic-Tac-Toe game as children, yet the appeal of playing this simple game stayed with us well into our adulthood. Its legacy has endured a long history as well—people have been playing it since ancient days of Rome, China, and Greece. Celebrated mathematician Martin Gardner relates the history of the game and explores its more complex variations, while also delving into the reasons we have been playing for as long as we can remember.