WarGames (1983)

During a secret live fire exercise of a nuclear attack, many personnel prove unwilling to launch a missile strike. To solve this issue, a supercomputer named WOPR is given control. David Lightman, a high school student and hacker, unknowingly connects to WOPR and starts a game of Global Thermonuclear War. The computer simulates an attack, causing panic at NORAD. Lightman realizes his mistake and tries to convince the authorities. With the help of his friends, Lightman manages to stop the impending nuclear war.