Mind game, where you play against the computer. You must advance to reach the red point, before the computer reaches the green one. You can only advance one place by turn, and the movements can be vertical, horizontal or diagonals, but you can never retrace a line. What you can do is to pass again over a point already used, and doing it will give you the advantage of being able to play inmediately, without having to wait for your opponent's move.
Click at the point where you want the next line to finish.