In the 1983 film WarGames, tic-tac-toe is used as an allegory for nuclear
war. In the climax of the film, the protagonist prevents an out of control
military defense computer from launching nuclear missiles by making
it repeatedly play tic-tac-toe against itself. After quickly learning
that good strategy by both players produces no winner, the computer
then plays through all known nuclear strike scenarios, again finding
no winner. The computer concludes that "The only winning move is not
to play."
