"Shall we play a game? How about Global Thermal Nuclear War?" Starring Matthew Broderick as young computer hacker Michael Lightman, and Ally Sheedy as his would be girlfriend, the science-fiction flick Wargames hit the scene in 1983. The movie was a success with critics, and was the highest grossing movies of 1983.
After it is learned that human nuclear technicians were reluctant to pull the trigger in times of need, the government decided to automate the nuclear process by allowing NORAD to program a computer, called the WOPR (Ware Operation Plan Response), to take care of the nuclear duties. While dialing various computers from his home while trying to find a game, young hacker Michael Ligthman stumbles across the WOPR, and decides to play one of the games listed on the machine: Global Thermonuclear War.
After finding the backdoor password, he starts to play, taking the side of the USSR, not realizing that WOPR does not consider it to be a simulation, nor does NORAD, who is preparing a real counter-strike. In the nick of time, Lightman manages to find the creator of the program running on WOPR, called Joshua, and he manages to convince NORAD to let the game play out, and to not launch any real nukes. Joshua has other ideas, and attempts to launch the missiles anyway. A way is found to teach Joshua a lesson in futility by having the computer play itself in a game of tic-tac-toe, and once Joshua realizes that all the games end in stalemate, it quits the launch and switches to a game of chess.