War Games is a 1983 American cult-classic written by Lawrence Lasker and Walter F. Parkes. The film stars a young-looking Matthew Broderick, alongside the lovely Ally Sheedy.
Other actors include Dabney Coleman, John Wood and Barry Corbin (of Northern Exposure fame).
Broderick, aka David Lightman, is a young hacker who inadvertently accesses WOPR, a military (NORAD) computer tasked with running nuclear war simulations.
Believing he is just playing a game, Lightman asks WOPR to load a title known as Global Thermonuclear War.
Unbeknownst to Lightman, the game causes a national nuclear missile alert and nearly kicks off World War III.
Background:
War Games is considered one of the most influential and popular hacker movies of the 20th century.
It has won numerous accolades, and was the topic of a 2008 Google symposium that paid homage to the film and its talented creators.