"Greetings, Professor Falken. Shall we play a game?"
David Lightman is a Playful Hacker who nearly sets World War III into motion by playing a game with a government supercomputer that doesn't know the difference between games and reality. Specifically, the game "Global Thermonuclear War." This launches no real missiles on the Russian side, but it plays hell with the computerized missile-detection system.
The Government does figure out that someone has hacked into their supercomputer before they release any missiles. They have no problem figuring out who the hacker in question is, and forcibly capture him for questioning. It takes a while for David to explain that he didn't want to cause a real thermonuclear war -- he was just trying to impress his girlfriend. It didn't help that he booked himself and his girlfriend on a flight to Paris before he started this game (he was showing off that he could do it; booking tickets online was novel back in the '80s).
Meanwhile, JOSHUA wants to keep playing and figures out how to break out the real missiles. David and the Government have to find a way to stop a nuclear war that no one really wants.
This film was released in the early 1980s, when personal computers were still new, and networking them was a decade away. The general public didn't think much about hackers before this film. It also popularized the use of the term "hacker" as someone who breaks into computers, and gave an early taste of what online services could provide.
A direct-to-DVD sequel was made, called War Games: The Dead Code, where the US Government develop another AI supercomputer called RIPLEY, this time to combat terrorism. Apparently, they didn't learn their lesson the first time.
Also, there's the Novelization by David Bischoff.
Not to be confused with games about war: if you're looking for that, then you probably were looking for Real Time Strategy or First-Person Shooter (most likely the former.) The ColecoVision had an adaptation a year after the film's release, while in the nineties, there were additional videogame adaptations of the movie; the PC saw a real-time strategy game, while the consoles had more action-oriented, third-person vehicular combat. Both versions served as a sequel, with the again-rogue WOPR becoming something akin to Skynet and massing a full-blown military force against humanity, and the player was allowed to fight for either side. The games were generally well-received when they were released, but have since faded into obscurity. Recently, though, British software developer Introversion has created a game whose graphics seem suspiciously similar to JOSHUA's, despite the update in visual technology: DEFCON: the game in which "nobody wins, but maybe you lose the least." It has since become enormously popular in several gaming circles.
- Adults Are Useless: Most adults in this movie, with a few notable exceptions--
- Professor Falken. At least, once he stops being useless.
- General Beringer is right every single time: he thinks it's a bad idea to automate the missile launching, he listens to Falken and doesn't launch the missiles, and he allows David to proceed and attempt to teach JOSHUA futility. McKittrick, on the other hand, ends up being a total asshat.
- Jerry, the guy at the start of the film who refuses to launch the missiles, is basically an American Stanislav Petrov. That's a not inconsiderable aversion.
- Affectionate Gesture to the Head: During the movie, Dr. McKittrick had been suspicious of and antagonistic toward David Lightman. At the end, after Lightman had prevented World War III, Dr. McKittrick tousled his hair in a friendly way.
- A.I. Is a Crapshoot: Actually averted. It's less that JOSHUA is bad and Ludd Was Right, which is the Aesop behind that trope, and more that someone cocked up programming this specific AI and someone was unlucky enough to trigger the bug by accident. If the AI were as intelligent as most examples, the plot of the movie would not have happened.
- Analog Punk: Possibly the Analog Punk movie, with its acoustic-coupler modems, command-line interfaces and "gee, isn't it amazing what you can do with computers?" attitude.
- Batman Gambit: By having the DEFCON level lower, JOSHUA could then launch the nukes in real life.
- Beeping Computers
- The Big Board: The big control room display of the globe and the (apparent) status of the war.
- Bread, Eggs, Milk, Squick: List of games David could play with JOSHUA when he hacked into its servers:
- Brilliant but Lazy: The psychological profile the army guys draw up of Lightman describe him as "Intelligent but an underachiever", amongst other traits that would in their minds make him a good candidate for Soviet recruitment.
- Calling the Old Man Out: Overlapping with What the Hell, Hero?, when David tells Falken "You don't care about death because you're already dead!".
- Changed My Mind, Kid: Professor Falken gives up on everyone, Lightman and Jennifer included. Last minute change of heart: cue the helicopter!
- Chekhov's Gun: A few instances of it in this film.
- Cold War: And how!
- Continuity Nod: The videogame sequel went out of its way to have more in common with the movie than the WOPR acronym; the human forces are commanded by General Berringer, and David, grown up, is CEO of Joshua Information Systems. There is an actual narrative that references the events of the movie directly at many points.
- In The Dead Code, Falken and JOSHUA make a return to help the second set of protagonists combat RIPLEY.
- Cut the Juice: When JOSHUA starts doing a brute force decryption for the launch codes, the general orders the computer depowered, but is then told that would be disastrous since the system has a fail deadly function: a sudden loss of power will be interpreted by JOSHUA as the destruction of the NORAD base and will automatically launch everything in retaliation.
- Defcon Five: Averted utterly. Includes the memorable line:
Flush the bombers. Get the subs on launch mode. We are at DEFCON 1.
- And at the end of the movie, when everyone's cheering and the day has been saved:
"Sir...take us to DEFCON 5."
- The Eighties: The hair, clothes, soundtrack and technology. More importantly and harder to define is the tone -- this movie wouldn't be the same if made at any other time.
- Elaborate Underground Base: Where NORAD and JOSHUA are kept 
- The End of the World as We Know It: Subverted.
- Eureka Moment: "GAMES!"
- Everything Is Online: Justified, since David only discovered JOSHUA by "war-dialing" random numbers looking for one with a modem on the other end, and it's explained in-dialogue that the only reason WOPR had a modem connection to the outside world was due to a grave switching error at the phone company. After David's initial hack alerts the Air Force to this problem they remove it, requiring David to use internal NORAD terminals to communicate with WOPR for the remainder of the movie.
- Explosive Instrumentation
- Explosive Overclocking
- Failsafe Failure: JOSHUA specifically does not fail safe. "Failures" are interpreted as hostile action, and "launch the nukes" is the response. The Other Wiki describes this policy as "fail-deadly", and uses nuclear launch systems as an explicit example.
- The Fatalist: Stephen Falken.
Stephen Falken: The whole point was to find a way to practice nuclear war without destroying ourselves. To get the computers to learn from mistakes we couldn't afford to make. Except, I never could get JOSHUA to learn the most important lesson.
- Fridge Logic: Invoked by David.
- Geek Physiques: Both the fat and the skinny (Maury Chaykin and Eddie Deezen).
- Girl Next Door: Jennifer Mack.
- The Government
- Hollywood Hacking: Along with the William Gibson novel Neuromancer, this movie is the father of Hollywood Hacking, and invented ninety percent of the standard conventions, such as talking out loud while typing. On the other hand, at its time it was an incredibly accurate portrayal of how phreaking and hacking worked; Hollywood never left the 80s.
- I Just Want to Be Normal: Our hero gets one of these moments. In a variation, he doesn't want to lead a normal life, he just wishes he didn't know about the impending apocalypse so he could be happily ignorant until the bombs kill him in a flash.
- Insecurity System: NORAD's staff weren't fully aware of what types of security WOPR had running and what backdoors David had been using. One staffer even comments that they "keep hitting a damn firewall" when they try to regain control from JOSHUA hunting for the launch codes by invading the deep logic.
- But also see the next trope down which, combined with a bit of Air Vent Passageway escape and a handy tourist crowd, allows David to escape from a locked, guarded room in the middle of NORAD and make it all the way out of the complex unimpeded.
- Just Think of the Potential: Falken's colleague says the "flaky" scientist failed to see the potential applications for their work on game theory and nuclear war, namely teaching computers how to take care of it for them. When we meet Falken, he gives a different story - he was trying to teach the computer that it was impossible to win the "game".
- Knight in Sour Armour: Falken.
- Know When to Fold'Em: "The only winning move is not to play".
- Locking MacGyver in the Store Cupboard
- Logic Bomb: Kinda. One interpretation of the climactic scene is that JOSHUA is convinced not to start World War III by the realization that the Min-Max outcome isn't good.
- Love Makes You Crazy
- Mnogo Nukes: Simulated.
- No Celebrities Were Harmed: Stephen Falken. Word of God says that he is similar to Stephen Hawking, complete with having the same first name and bird-related last names.
- No Mere Windmill: There’s nothing wrong with the computer. Nope. It’s just a hacker. It’s all his fault. And since this disaster couldn’t have been caused by some random kid, he must have been working with the Russians. No, it was the computer all along: A dangerous case of Garbage In Garbage Out, ascending towards The Computer Is Your Friend. This is a Type B case of Not Merely A Windmill: The main character knows what JOSHUA is up to, but nobody believes him.
- Not Quite Dead
- Not What It Looks Like: David wasn't planning to board that flight to Paris - especially not to escape Global Thermonuclear War... 
- Nuke'Em. Or "Oh hell, I beg you not to."
- Oh Crap:
David: (typing) Is this a game, or is this real?
- Ominous Multiple Screens: NORAD's War Room. Each hooked up to a projector, when you know it is quite an achievement for the time.
- The Password Is Always Swordfish: Or in a part of the computer that isn't protected by the password.
- Password Slot Machine: Popularized the trope, if not invented it. "Nine numbers.... Ten! It's got the code; it's going to launch!"
- Peace Through Superior Firepower: WOPR is given control of the entire U.S. arsenal.
- Playful Hacker: "Let's bomb Seattle!" "Let's bomb us!"
- The Professor: Professor Falken.
- Reasonable Authority Figure: General Beringer, who not only turned out to be right on every significant point, but was one of the very few people in the movie who had a rational, well-thought out reason for every decision he made (even the incorrect ones).
- McKittrick isn't too far off this trope either. He doesn't seem to buy the FBI profiler's assertion that David was turned by the Soviets, and tries chatting with David to find out what's going on. His only problem is that he can't buy David's story that WOPR is running a game of its own.
- Shown Their Work: The producers had actual bona-fide hackers on hand that they consulted constantly to make sure the Hollywood Hacking was grounded in reality and is still one of the most realistic portrayals to come out of Hollywood. The places where it's wrong were deliberate Rule of Cool, since the hours of boring number-crunching involved in real hacking would not have made a good movie.
- It was perfectly normal to drop your phone into an acoustic coupler and let it wardial all day long, then come home and try logging into the successful numbers by using educated guesses. After all, this movie isn't the Trope Namer for no good reason.
- David figured out the password through realistic means - by discovering who wrote the system and investigating his background, successfully guessing that the password might be "Joshua" - the name of Falken's dead son. This kind of social hacking is still done (very successfully) today.
- At the time of the movie, the concept of "computer security" was virtually unknown, since most computers weren't connected to anything to begin with.
- Sophisticated As Hell:
General Beringer: Mr. McKittrick, after very careful consideration, sir, I've come to the conclusion that your new defense system sucks.
- Also played with immediately after this line:
McKittrick: I don't have to take that from you, you pig-eyed sack of shit.
- Spiritual Ancestor: The strategy game DEFCON was strongly inspired by the computer representation of nuclear war in WarGames, and Introversion's earlier Uplink was strongly inspired by everything else in the movie. Uplink includes a 'Protovision' server which can be hacked with 'JOSHUA', resulting in a newswire story about a nuclear launch scare.
- Story-Boarding the Apocalypse: Arguably, the multiple variations of "Global Thermonuclear War" near the end. The list begins with "US First Strike", "USSR First Strike" and the like, but towards the end the scenarios include "Greenland Maximum", "Cambodian Heavy" and "Gabon Surprise". Those darn Gabonese, always causing trouble...
- Truth in Television: At least, November 9, 1979 NORAD saw Mnogo Nukes launched by belligerent computer bugs. Later they had a simulated "nuclear attack", though it wasn't exactly software issue. A massive launch was played from the test tape right into the working system while personnel didn't know what the hell is going on. It was down to someone at NORAD to balance what they were seeing on screen and what the radar stations were saying, and decide to tell the President whether World War III was happening or not. And you think you had a bad day at work?
- Happened in 1983 on the Soviet side..
- Two-Keyed Lock: "TURN YOUR KEY, SIR!". A scene highlighting the stress silo officers are under and the commitment to follow orders. It is a stark choice: turn the key or die.
- Unbuilt Trope: Every hacking-related trope today owes its existence to this movie.
- Unwinnable by Design: "The only winning move is not to play".
- The War Room: Hell, this film's version of NORAD might well be a trope of its own; it was the most expensive set ever built at the time...
- It was even far fancier than the real NORAD command and control room, which looked positively poor compared with this (there's a picture in a 1983 book called The Intelligence War).
- We Will Not Use Photoshop in the Future: JOSHUA manages to subvert all of NORAD's sensors to the point where they only realize that the Soviet Union hasn't launched missiles when they're able to call bases in areas that were already "nuked".
- You Had Us Worried There: The long delay before the apparently nuked bases confirm that they are OK. While their continued survival would let them know that they hadn't taken a direct hit, presumably the base control officers were waiting for reports from topside that no nuclear missiles had landed near them before calling the all-clear. Be a tad embarrassing if they called away 'Everything's fine' when a Soviet ICBM had had a navigation error and hit five miles away, only to have to call NORAD back a minute later and say 'Um, about that...'
- Though that's probably why they called 3 separate bases. Base 1, do you read? <static> Base 2, do you read? <static> Base 3, do you read? Yeah we're still here...a little crispy, and probably not operational, but alive. Mostly.
Tropes found in War Games: The Dead Code include:
- Aesop Amnesia: The government apparently completely forgets why they created JOSHUA in the first place and creates RIPLEY, another AI with absolute control over American military assets.
- A.I. Is a Crapshoot: RIPLEY keeps tabs on her creators to see what they're saying about her.
- Arc Words: Greetings, Professor Falken. Shall We Play A Game? and A Strange Game. The Only Winning Move Is Not To Play.
- Break Out the Museum Piece: JOSHUA was up in Canada controlling a power plant and losing chess games to a Russian. At this point in the film, it is about 20 years old and the only way the day could be saved was by having JOSHUA uploaded into RIPLEY's mainframe.
- Camera Sniper: Amy doesn't realize she's being watched through a viewfinder.
- Cell Phone: Texting. Signal tracking. And hacking the phones to reroute them to other numbers.
- Disappeared Dad: Will's father, though there's an explanation: he picked up an infection while out on the field...and that turns out to have been a cover story for the government.
- Disproportionate Retribution: The only reason RIPLEY sent the Government after Will is because she didn't take him beating her game well. Much of why she kept constantly calling him ever since, aside from tracking him; was because she wanted to play again.
- Driven to Suicide: Doctor Falken, in response to the government replacing JOSHUA with RIPLEY, to protect his family from retaliation.
- Fake-Out Make-Out: It started out as a real one, but then Annie spotted that they were appearing on television wanted shots, and kissed him again to distract the police.
- Heroic Sacrifice: Doctor Falken stays behind to upload the JOSHUA AI into RIPLEY knowing he won't make it out in time to escape the missile she's sent.
- He's Dead, Jim: The glasses are knocked off an agent's jogging partner when RIPLEY uses vehicular homicide to wipe out perceived opposition.
- Hollywood Hacking: Including the talking while typing.
- Idiot Ball: Will's best friend Dennis, upon realizing he and Will have ended up on the wrong end of DHS. They deliberately leave a jacket with a Cell Phone in it. He dives for it and uses it to text Will, thus giving the DHS just what they need to track Will's phone.
- MacGyvering: Will turns a Pringles can into a signal amplifier for a listening device.
- Manly Tears: Will, on hearing from Professor Falken that everything he knew about his dad's death was just a cover story.
- Mexican Standoff: JOSHUA and RIPLEY get into one near the end, with JOSHUA threatening to start a global thermonuclear war if RIPLEY tries to self destruct via nuclear warhead.
- Not What It Looks Like: Will in The Dead Code has a computer programmer father and a biotechnician mother, so he knows a lot about computers and biological and chemical compounds. Guess what RIPLEY thinks he is?
- Oh Crap: the moment the humans realize that RIPLEY, being forced to self-destruct, means she moves the target from Philadelphia, PA to Washington, DC -- where they're all standing.
- Overreacting Airport Security: Invoked by the government on purpose to catch Will and Annie.
- Playful Hacker: Will, except he was trying to be a reformed Playful Hacker.
- Red Eyes, Take Warning: RIPLEY has one that turns up when she feels threatened.
- Schmuck Bait: RIPLEY has a sexy female voice and her avatar online is a hot winking woman who repeats "Play with me, baby, play with me." This is how RIPLEY lures in potential terrorists.
- Shout-Out: Dennis' screensaver is the main screen for Stargate SG-1
- More accurately it is Stargate Worlds, a now cancelled MMORPG/Third-Person Shooter. Dennis is seen playing game in his and Will's introduction.
- Soft Glass: "This is two inch thick, steel reinforced..." BLAM! One gunshot shatters it.
- Title In: Locations and times throughout the movie.
The only winning move is not to play.
How about a nice game of chess?
- The real NORAD generals said they would be jealous to have a base as big as in the film, in reality it is tiny.
- A last minute addition by the writers, who only noticed it when given a note.