Rules for Tic-Tac-Toe

1. 1.) The game is played on a grid that's 3 squares by 3 squares.
2. 2.) You are X , your friend (or the computer in this case) is O . Players take turns putting their marks in empty squares.
3. 3.) The first player to get 3 of her marks in a row (up, down, across, or diagonally) is the winner.
4. 4.) When all 9 squares are full, the game is over. If no player has 3 marks in a row, the game ends in a tie.