TicTacToe, is a pencil-and-paper game for two players, X and O, who take turns marking the spaces in a 3×3 grid. An early variant of Tic-tac-toe was played in Roman Empire, around the first century BC. It was called Terni Lapilli and instead of having any number of pieces, each player only had three, thus they had to move them around to empty spaces to keep playing.