XKCD and Tic Tac Toe

XKCD has a neat image that lays out ideal Tic Tac Toe strategy.  The image is a little complicated to read at first, but once you figure out the design of his presentation, it's pretty great, both from the game perspective, and also from a visual display of information perspective.

I've had students write ideal tic tac toe players as an exercise in my computer programming classes, and they sometimes struggle more with the strategies than with the programming parts.  This might help, although interestingly, because it's the ideal strategy, it doesn't actually include the decision trees for sub-optimal starts (i.e. where you don't pick a corner as your starting space).

Also interesting is that because Tic Tac Toe is such a symmetric game (i.e., there are only three types of spaces, center, corner, and middle-edge), the image Randall Munro created actually contains some neat visual symmetry, which, along with the fractal nature of his presentation, is cool to look at.  He's a very clever guy, and I love it when he does this kind of thing.