Ultimate Tic-Tac-Toe is a Tic-Tac-Toe game that requires a lot more planning and thinking, but is still pretty simple to play. There is a big Tic-Tac-Toe board and in each of it's 9 squares, there is a small Tic-Tac-Toe board. Where a player plays on a small board determines which small board the next player gets to play on. When a player wins a small board, they get to place their X or O in that square on the big board. The player wins by getting three in a row on the big board.