Computer whiz kid Will Farmer's (Matt Lanter) neighbor Massude comes to Will having a problem with his computer. Will takes the computer and hooks his own up to it and discovers that Massude's brother is using his online banking to make huge profits. Since he needs $550 to go on a chess trip, Will steals $500 from Massude's account to gamble on an online gaming site that uses games that are based on terrorist attacks. Will later discovers that his best friend Dennis changes it to $5000. He ends up winning $25,000, with the aid of his mother, who knows about biological agents. Little does he know that the online game he plays is actually part of a sophisticated piece of U.S. government spyware designed to find potential terrorists based on how well they perform and bet on the games. The spyware program is run by a new, advanced artificial intelligence system called RIPLEY (an acronym that is not explained in the film, nor by its makers), which has ultimate control over every American electronic system in order to combat terrorism.
Homeland Security, now believing Farmer to be a terrorist, sets out to apprehend him. During Will's return home one day he finds Massude is being arrested on account of suspected terrorism, and gives Will an envelope full of cash as payment, which he uses to finance his trip. Unknown to him and Homeland Security, RIPLEY is misinterpreting the data and is overreacting to the situation. On his arrival to the airport, he finds that there is an abnormally large number of security guards. He manages to slip away and meets up with his friend Annie.
In the streets, he manages to crack the government network, only to be found by the police, and as Annie pointed out, a man in an overcoat. The cops chase the couple until they get lost in the subway systems. Will manages to find a way out, and they meet the man who was watching them from the doorway, he says that he nearly started World War III, and to meet them at his truck. He is revealed to be Professor Falken, who had helped design RIPLEY. They travel to a small power plant outside a dam (during the trip, Will and Professor talk about the sensitive points of the past of each one, revealed before the trip to the power plant), where the professor shows them a dilapidated computer called WOPR (War Operation Plan Response) from the original WarGames film, which is operating the power grid at only 5% of its potential efficiency. Professor Falken had designed this computer to aid in the planning of a global thermonuclear war if it was needed. Falken re-activates WOPR with his backdoor password "Joshua" (the name of Falken's deceased son as well as the name the professor uses to refer to the AI that is WOPR). Meanwhile, RIPLEY is led to believe that Philadelphia has been hit by a bioterrorist attack and decides to halt the spread of the bioweapon by hijacking a Predator drone with missiles and a nuclear warhead on board and use it to destroy the city.
Falken instructs Joshua to attack RIPLEY with a faux script full of cultural references. Joshua starts flooding RIPLEY's system with games, which seem to be overloading the system, but then RIPLEY shuts down and reboots to successfully rid herself of the games.
Rebooted, RIPLEY redirects the Predator drone, which she uses to destroy the facility housing Joshua. Joshua warns the professor that RIPLEY's advancing attack would result in obliteration; so Will and Annie flee the facility just before it gets blown up by the drone's missile, with the professor, who was dying from pancreatic cancer remaining in the building at the time, last seen typing extremely fast, finishing with something that looks like an "Enter", and saying "Goodbye, Joshua".
The couple are arrested by Homeland Security and taken to the room where RIPLEY is stored, only to find that she has taken control over the system, and they discover that Professor Falken has transferred Joshua via an email (having changed the backdoor password to "Max", which was the name of the real Joshua's teddy bear) to them to help them stop RIPLEY. They first try to use WOPR and internet users to stage a denial of service attack, which causes RIPLEY to overload. RIPLEY, knowing that she has been compromised by WOPR, decides to self-destruct by launching a nuclear warhead at Washington D.C.. Annie remembers a chess game known as "Suicide Chess" where if you win you lose. Will programs WOPR to play Russian Roulette, where the goal is to lose as opposed to winning. They again pit WOPR against RIPLEY by granting him access to one of six American nuclear launch codes. RIPLEY and WOPR play through two nuclear attack scenarios both resulting in total annihilation; however, the codes for those missiles are unavailable. The third scenario presented is a nuclear attack on Washington D.C. Having learned the concept of futility presented by playing a game where if you win you die, RIPLEY stops responding after the scenario is played out, also resulting in total annihilation, and the weapon is available. Joshua asks if they are still playing at which point she says, "A strange game. The only winning move is not to play", just as Joshua had said at the end of the original film after learning how to play Tic-Tac-Toe.
After RIPLEY relinquishes control, Will asks WOPR if he really would have launched the missiles if RIPLEY had decided to continue playing. WOPR replies, "Yes, the human race is finished." before revealing, "That was humor."Matt Lanter as Will Farmer
Amanda Walsh as Annie D'Mateo
Colm Feore as T. Kenneth Hassert, and Voice of WOPR ("Joshua")
Chuck Shamata as Bill Carter
Maxim Roy as Tina Rashe
Nicolas Wright as Dennis Nichols
Gary Reineke as Stephen Falken
Susan Glover as Gail Farmer
Trevor Hayes as Agent Aaron Scott
Claudia Ferri as Agent Bolton
Vlasta Vrána as Ivan Prokosh
Ricky Mabe as Newman
Claudia Black as Voice of RIPLEY
Russell Yuen as David Chen
Robert Higden as Mr. Baron
John Maclaren as Norman Paget
John Koensgen as Martin Cavanaugh
Alberto Delburgo as Sayid Massude
Lucinda Davis as Joleen Dupree
Neil Napier as Teacher
Matthew Raudsepp as Doug Maltz
Danny Blanco as The Groom
Alain C. Gauthier as Internet Café Guy
David Schaap as General Stradler
Jean-Robert Bourdage as Hot dog Vendor