(Not "War Games") A 1983 film about a schoolboy cracker using a wardialer to try to break into a games company's computer and accidentally connecting to a backdoor into "Whopper", a ficticious c3 computer at Norad (USAF). He then procedes to unwittingly initiate global thermonuclear warfare. Playing naughts and crosses finally teaches Whopper that the only way to win the game is never to play.

imdb.