I just played a guy in Tic Tac Toe online (using the free Freeverse games being offered on mac.com.
If I get center square as the first move, I win 50% of the time on the next move if the other user picks his first square at random: a side square means I win. Then, if he picks corner, I win 66% of the time if he picks his next square at random (it must be one of the two corners, as I select the opposite corner). So overall, for random picking of the first two moves, I win 83% of the time, and if he picks with some reason (meaning he would pick one of the two closest sides to his first corner on his second move), it is 75%.
Unfortunately, this bloke I played against picked a side square in the first game, then a corner and then a side in the second. Losing two games in a row of Tic Tac Toe must have flustered him, because in the next game he picked a corner and then another corner, but then he didn't pick to block my only winning move and I won the third game. He picked side again in the fourth, and then finally he picked two corners and blocked me in the fifth.
All this to say it must be really humiliating to lose four games in a row of Tic Tac Toe.
My first Perl program was a Tic Tac Toe CGI