At a video-game arcade in 1982 with his friend Will Cooper, 13-year-old Sam Brenner discovers he can master the games by spotting and memorising patterns in them. Participating in a video-game championship, he loses in a match against obnoxious arcade player Eddie Plant in Donkey Kong. A videocassette containing footage of the event is included in a time capsule that is later launched into space by NASA, in hopes of reaching any extraterrestrial life.
33 years later, Brenner has become an installer of home-theater systems while Cooper is the President of the United States. In Guam, a U.S. military base is attacked by UFOs of Galaga that turn pieces of the base into small glowing cubes and one of the soldiers is abducted.
While working at the home of divorcée Violet Van Patten and her son Matty, Brenner is summoned to the White House. To his surprise, he finds Violet is also headed there as a lieutenant colonel. Upon seeing the video footage and meeting with Ludlow “The Wonder Kid” Lamonsoff, a friend he made at the video game tournament earlier, Brenner speculates that the aliens have found the videocassette images in the capsule to be a declaration of war and are attacking them with spacecraft resembling classic video game characters. This is affirmed when the aliens interrupt a television broadcast, challenging Earth to a battle where if the aliens win three rounds, they will conquer the Earth. Brenner and Cooper are unable to stop one of the attacks as Arkanoid paddles sling balls of light to destroy the Taj Mahal, and another person is abducted.
Brenner and Ludlow train Navy SEALs to play the old games. Violet develops light cannons that are effective against the aliens. In London, the aliens attack in the form of the video game Centipede, but as the soldiers are unable to beat them (as they forgot to shoot at the heads), Brenner and Ludlow step in and shoot them down. Following the victory, the aliens send their congratulations and a “trophy” in the form of the dog from Duck Hunt to an old woman (who appeared earlier at the London attack).
Ludlow and Cooper retrieve Eddie, who had been serving a prison sentence for fraud. In New York City, the team discovers it must participate as the ghosts against Pac-Man. Toru Iwatani, the creator of Pac-Man, flees after his hand is bitten off by him. Using four coloured Mini Cooper cars, Brenner, Ludlow, and Eddie overcome the task, but Violet notices that something about Eddie is off, as he moved at supersonic speeds around the board. They win Q*Bert as a trophy, but the aliens (as Hall & Oates) later declare that someone cheated and the contest for the planet has been forfeited. Matty discovers Eddie used a speed cheat which was written on the back of his shades, thus revealing that he is the one that cheated. When the aliens’ mother ship suddenly appears, Eddie flees from it, but Matty gets abducted by the aliens.