TicToku is a combination of two classic games – TicTacToe and Sudoku. TicToku is a free and fun way for people of all ages to challenge each other to a strategic math based game. Playing against a friend or the computer, players strategically place numbers from 1 to 5 on the playing grid to add three numbers across, down, or diagonally to achieve the target. You can only play each number from 1 to 5 once, but you can also use your opponent’s numbers to reach the target.