How to beat little kids at tic-tac-toe

I'm overly proud of this

As everybody knows optimal play with tic-tac-toe is a draw. Often little kids work this out themselves and are very proud of it. You might encounter such a child and feel the very mature and totally reasonable urge to take them down a peg. How to go about doing it? Obviously you’d like to beat them but they already know how to win in the best lines, so what you need to do is take the first move and play something suboptimal which is outside their opening book.

This being tic-tac-toe there are only three opening moves and two of them are good so you have to play the other one, which is moving on an edge. You want to play the edge which your opponent is least likely to have practiced. Assuming your opponent is learning to read in english they’re being taught to scan from the upper left starting by going to the right, so the last edge they’ll practice is the center bottom, and that’s where you should make your first move.

Some of the moves which the opponent can play now lose, you can work those out for yourself. The most common non-losing move is to reply in the center. At this point moving in both the upper corners or middle edges are good moves. Maybe you’ll even be able to beat this kid more than once. The better variant of both of those moves is on the right, again because it’s the one which they’re least likely to be familiar with due to read order.

Those same tricks work well against chatbots. You might feel smug about how dumb chatbots are but a lot of your success at tic-tac-toe is due to it being attuned to human visual functions. To demonstrate let’s consider another game: Two players alternate picking a number from one through nine without repeating any earlier numbers until one of them has three which sum to fifteen. You probably find this very difficult and confusing. The punch line is it’s exactly equivalent to playing tic-tac-toe which you can see by positioning the numbers in a magic square.