The Crown Game: If you take the Crown and sit on the Throne in less than five minutes, your teams wins the round.
Hide-And-Seek: Tap the Seeker's badge and you auto pass into the final examination. Also, your team wins.
Trustworthy Room: When Viole captures Yeon's room, he instawins.
Code Geass, during the Final Battle of the second season. Lelouch, his army obliterated and Suzaku defeated by Kallen, seizes control of Damocles. This is Justified, because with Damocles under his control, it's either surrender to Lelouch, or Lelouch nukes the entire world with impunity.
Risk.You're whittled down to a handful of tanks and a couple territories? If you finish off the player whose defeat was your winning condition, you've won.
For those unfamiliar with the chess rules: you win by putting your opponent in checkmate, which is when the opponent's king cannot escape a threat. This wins the game even if you have two pieces left against your opponent's sixteen (though pulling that off would require Epic Fail from your opponent).
And of course, there's the Fool's Mate: 1. f3 or f4 e6 or e5 2. g4 Qh4++ . That's about as instant as chess gets!
In Zombie Plague, the humans win by barricading every window and door, with no zombies in the house. 4 zombies can break down any barricade. Human victory often comes with the sealing of an unimportant window somewhere, while a fourth zombie joins the group of 3 about to break down the front door.
The board game End of the Triumvirate is designed around this trope. With three players and three completely different victory conditions, the winner is usually the one who can keep all three fronts up in the early game, then suddenly throw two of them away for the third when he knows he can win.
In the Lovecraft themed board game Arkham Horror, there are tons of instant fail conditions (Doom Track fills up, Too many gates are open at once, all three acts of the King in Yellow are performed...), and the normal ways to win are to either seal gates or kill the Ancient One after he awakens, which is difficult for most (and impossible for Azathoth, since his attack is Destroy the Universe). But if you manage to use all six elder signs on the board, even if the Ancient One would awaken the next turn, you win instantly.
In the original versions of (The Game of) Life, if you reached the Poor House with "little or no money", you could pick a number from 1 to 10 and spin the wheel, and if it landed on your number, you became a "Millionaire Tycoon" and won the game instantly.
In the Discworld board game, Ankh Morpork, each player has a secret identity with instant win conditions depending on factors such as the property they own, how much Trouble is being caused etc. If you are Commander Vimes, all you have to concentrate on is stopping these conditions happening, as if you reach the end of the draw pile with no one else winning, you've won!
In the Star Wars game The Queen's Gambit, if the Naboo side gets Anakin to the Droid Control Ship, all the droids (which is almost everything the Trade Federation player has) instantly deactivate. As long as Naboo still has 3 pieces in the palace, they win.
The final action scene in Star Wars: A New Hope in which Luke Skywalker uses the force to defeat the Death Star's one weak point in the nick of time with his comrades dying on either side of him is an example of this trope.
In Return of the Jedi, the battle is basically won once the rebels on Endor's surface blow up the shield generator. Despite being pincered between the Death Star and a huge Imperial fleet, and taking serious losses, the battle's basically won as soon as a few fighters and the Millennium Falcon conduct an Airstrike Impossible.
In The Butterfly Effect the protagonist repeatedly engages in near-suicidal acts then rushes back to read his journal transporting him further back in time, thereby hitting a reset button to his life while the angry fellow prisoners / men in white shirts beat down the doors. We next see him at the same point in his life, everything is restored back to normal.
In The Avengers film, the Chitauri armies keep coming and would eventually wear the team and New York's defenses down, except for Black Widow shutting down the tesseract and closing the portal, stopping the invasion cold. A secondary Instant-Win Condition is invoked by Iron Man when he pulls a nuke into the portal and destroys the Chitauri mothership, breaking the control over the Chitauri army on earth and shutting them all down.
Jousting in A Knight's Tale has this. Knights score 1 point for breaking a lance on their opponent's torso, or 2 for the head. The knight with the most points after three lances wins. But if a knight can knock his opponent off his horse, then the knight wins immediately, regardless of the points.
In Ender's Game by Orson Scott Card, the former trope namer ("The Enemy Gate Is Down"), Ender realizes (or remembers from his time at Salamander) that he doesn't have to disable all of the opposing soldiers in order to win the Battle Room situations, like everyone had assumed—he just had to get five of his to the gate. The rules are promptly changed, but it does allow him to win a battle against a double-size army in entrenched defensive positions.
This comes up again in the final training level at Command School. Ender rightfully figures that the entire enemy fleet, outnumbering his own by hundreds to one, is worthless compared to the planet they defend and instead launches a suicidal attack to destroy that planet. Snagging the fleet is just a bonus.
Both scenarios were pretty much unwinnable with the conventional approach and thus required the lateral—and very much desperate—thinking to win. It's also worth noting that in the second example, Ender has crossed the Despair Event Horizon and is trying to get kicked out by doing the unthinkable. (And in the first example, he's on the very edge of the horizon and he just wants to mock the instructors.)
Applies to Lord of the Rings, where the strategy to defeat Sauron is not to beat him in direct battle, but to sneak the Ring of Power into Mordor and destroy it. The destruction of the Ring kills Sauron, unmaking things made with his power (his fortress Barad-dűr), and confusing and thusly incapacitating the parts of his armies which were more directly controlled by him.
An interesting variation almost occurs in the Discworld novel Interesting Times. Cohen the Barbarian successfully usurps the throne of the Agatean Empire simply by sneaking into the Forbidden Palace and sitting on it. Unfortunately, while this works for most of the cowering population, the Agatean warlords are none too happy and he ends up having to fight a war anyway.
In the post-Apocalypse novel Malevil, relying on an Instant-Win Condition becomes the plan of attack near the end of the novel. The Bigger Bad is marching his army toward the hero's castle, he rules his men with fear and bad luck has cost him his two best lieutenants. If they can kill him and his last second-in-command then his army should disband. They have to succeed because while he can't take the castle in a single battle, they won't be able to win a prolonged guerrilla war against him.
Live Action TV
In Run For Money Tousouchuu (the original Japanese version of Cha$e), all you had to do to win the grand prize was avoid getting tagged by a Hunter until the time limit runs out. Even if you're running as fast as you can with a Hunter right behind you and gaining, you still win as long as the countdown hits zero before you get tagged (and at least one player has won this way on the show).
In Robot Wars you can be battered, smashed, running on the last bit of engineering, and if you can put your opponent in the pit of oblivion, you automatically win. The same applies to your opponent becoming immobilised, either by a mechanical malfunction or through its own actions (e.g. the early Razer defeat when it pinned itself to the floor with its wheels in mid-air), although it would require 30 seconds of them not moving.
In the famous two-part episode "The Best of Both Worlds" from Star Trek: The Next Generation Data invokes the instant win condition by switching the entire Borg Cube into regeneration (read: sleep) mode and in the process activating the cube's self destruct mechanism, stopping its attack on Earth.
Many game shows that had a rule that, upon winning enough games and returning to the bonus round, won the grand prize automatically. Usually, this was after a fifth day of a contestant's reign, in which case they were simply given the prize without having to play the bonus round and (often) retired undefeated.
Specific other examples:
The Joker's Wild: Drawing three jokers in a single spin during the main game automatically won the game at $500, provided two conditions were met: 1. The contestant correctly answered a question in a category of his choosing, and 2. His/her opponent (if they were the champion) was unable to spin a combination that would allow him/her to tie the score at $500. In early episodes, the game immediately ended without anything further needing to be done, but the aforementioned rules were added once a contestant – a champion – spun a triple joker on his first spin, meaning the opponent didn't get even a chance to play.
Wheel of Fortune: Provided the contestant can correctly pronounce the displayed puzzle, a contestant filling in the puzzle completely on his turn won automatically. (The video game version, which does not require the reading of the puzzle aloud, automatically awards the contestant the win.)
Every platform game is like this. If you can win enough points to advance to the next level, even if you're on the verge of death.
In the 3D games, no matter the situation, as long as you get to the Star or Shine Sprite without dying, the Star protects Mario from any major trouble in the area. It doesn't matter if in the middle of an island sinking into lava, the bottom of the ocean with hardly any oxygen, or in the case of Super Mario 64, doing a victory dance on a bottomless pit/the middle of the skynote this one was averted in the remake.
Kaizo Mario World, the Trope Namer for the Kaizo Trap, goes out of its way to avert this trope. Unless you've taken care to cover the pit beyond the finish line, grabbing the flag will cause Mario to happily walk to his death.
Super Mario Galaxy 2 takes this to the extreme. Most of the Green Stars actually require you to leap to your death. As long as you can manage to collide with the star along the way, you're golden.
Justified, since the star makes you float and transports you back for inexplicable reasons.
In the Super Smash Bros games, you can still win in many situations even if you're careening towards certain doom so long as your enemy does so first.
One method that invokes this same technicality is to swallow the last enemy as Kirby and fall off the side. For some reason, the enemy in Kirby's belly will count as having been defeated first, leading to an instant win with Kirby some minuscule distance away from his own death. His "throw" moves work similarly.
Bowser does it better. He can grab an enemy and body slam them into the floor. If you move in midair to over a pit during this attack, Bowser can end up pulling the enemy along on a suicide dive, the enemy dying a moment before Bowser.
In the original, this bug only worked on The Dragon Metal Mario, but other enemies could be beaten using a variation.
It can be done in some manner by DK, Diddy Kong, and Ganondorf, etc.
Partially averted in Brawl, where a bug in the code can result in either an instant victory or Sudden Death, depending on controller order. The "Suicidal KO" rule used in tournament play fixes this.
A situation universal to every Smash Bros. game, combination of characters, and rulesets is that if the remaining characters have all been sent flying, whoever gets KOed last wins. Thus, someone who got punted first could still win the match as long as the game has declared everyone else KOed before him or her (as the length of time between the final blow and declaration of a KO can vary depending on the stage, the direction of the launch, and the location of the final blow).
In Civilization, you can snatch victory from the jaws of defeat (and your rivals) simply by accomplishing a victory condition - any victory condition - before they do. Enemy at the gates? Get that ship to Alpha Centauri and you win. Another Civ about to colonize the stars? Stomp him flat and conquer the globe. Diplomatic and cultural victories are also possible in the later games, allowing even Civs with weak militaries and backwards technological development to come out ahead of their competition. Alpha Centauri also included an economic victory by cornering the global energy market.
Domination victory is acheived when only one player still has their orginal capital, so even if the enemy has 15+ cities spitting out military units, you win if you take their capital. Civ IV's cultural victory conditions are a great example of this trope. A strong alliance can burn all but three of your cities to flames (and be about to take care of the last three), but if you can reach "Legendary" culture levels in those three cities, instant win.
It can get even more absurd, but not less fun, in the mod Rhye's and Fall of Civilization, which focuses on accomplishing specific historical goals, quite a few of which involving building something or researching a specific technology. For instance, as the Mayans, the Aztecs and Europeans may have reduced you to maybe five squares of Central America, but as long as you researched calendars and build the Temple of Kukulkan, you'll automatically win if you live to 1745.
Even weirder is the space race victory in the Civ I, Civ II and the Beyond the Sword expansion for Civ IV. You win when the spaceship reaches Alpha Centauri (not just when you launch it). If your opponents wipe you off the map in the time it takes it there, you still lose, even though you colonists will still arrive at Alpha Centauri. Or conversely, if your opponent has already launched the spaceship, killing him quickly (nukes are your friend there) will stop him from winning.
A common case in Supreme Commander, where the default victory condition is 'assassination'. If you kill your opponent's Armored Command Unit, they're wiped out. Many games are ended by a single large wing of strategic bombers punching through a layered defense, or a single nuke, aimed to take out a single unit.
This is justified, at least in the story mode - the ACU is the only manned unit, and the other units' AI isn't sophisticated enough to continue strategic combat in its absence.
It's a holdover from SupCom's spiritual predecessor Total Annihilation. In the campaign and the default multiplayer settings destroying a faction's Commander would instantly detonate every single one of their units and structures- effectively a shortcut to the more plausible 'destroy all enemies'.
In the Grand Theft Auto series, your Wanted level will be reduced to zero immediately upon finishing many missions. This can lead to a case where you have a dozen police cars surrounding you as you reach your objective, then all of them decide "Oh, he won. Let's go get some coffee."
Also, the Saints stores in Saints Row The Third. You walk into a store and instantly your wanted level disappears. Why? Because your (invisible) boys are guarding the store and it is Saints territory. Which is enough to scare off tanks and AP Cs sent by someone who openly declared war on you.
Also works by going into a Pay 'N Spray, even when the damn Army is chasing you (unless you have a vehicle they won't touch, or there is an APB on the mission vehicle). You'd almost think Chief Wiggum was leading the police in those games.
* car leaving Pay N' Spray* "Let him pass boys, we're looking for a blue car"
And then you have Chinatown Wars, while Pay 'N' Spray will remove your wanted level with a fresh coat of paint, they'll outright refuse to do so while there are any active cops or police cruisers in the vicinity. Police cruisers make up about a third of the traffic on Chinatown Wars take of Liberty City, and your chances of actually getting anywhere near a Pay 'N' Spray without cops trying to ram you off the road approach practically zero. Still, heat magically disappears if you trigger a mission, complete a mission, or walk into your safehouse and rest for six hours even in full view of the police, as it has from San Andreas.
Going to sleep will even work if the police are in your house, or even if they're shooting at you as you climb into bed.
Has been known to happen in Double Conquest maps in Battlefield 2142. One team will have the other down to only a few tickets until defeat while still having over a hundred left themselves, when a sudden strike from behind sweeps across the field capturing all their spawn points and wiping them out. Without anywhere to spawn, all those tickets are worth NOTHING. (Of course, this is very rare as a team which ends up that far behind on tickets most likely lacks the coordination to mount this kind of counterattack.)
In the Command And Conquer series (and many similar games), many missions just involve getting to a particular MacGuffin. Once you're actually at it, even if half the enemy army is about to converge at your position in what will surely be a one sided victory for them, the mission ends and you miraculously escape off-camera.
Except for that one mission in the first game where you have to escape with it: Nod mission 6.
Averted in Red Alert 2, where lose conditions are checked even after the victory banner is shown; one Allied mission requires using Tanya to destroy a few key buildings in a Soviet base, and Tanya can be overrun and killed if you complete your objective without clearing out the enemies (especially attack dogs) nearby - the victory banner is shown and cheering starts, then Tanya dies and the Mission Failed banner appears over the victory banner and you must start the mission over.
In Outpost 2, every mission is a race against time. If you're playing as Eden, the bacterial nightmare called the Blight encroaches on the map and starts destroying your base, consuming it entirely if you dawdle, resulting in an automatic mission failure. Plymouth faces a similar threat from volcanic activity: If you take too long, you'll get swamped by lava. The thing is, even if the Blight or the lava is just a tile or two away from your Command Center, if you can otherwise fulfill the mission conditions, your colonists are all packed up and ready to escape before the disaster consumes everything.
The game does attempt to avert this somewhat - a constant requirement across all base building missions in the Outpost 2 campaign is to be sure you have enough evacuation transports constructed for your current population, and have materials for the new colony already loaded into trucks and ready to leave at a moment's notice. If this isn't the case, either by not building them or the transports somehow getting destroyed, victory will not occur. Indeed, in the closing missions, you're reminded to keep your population at a steady figure, too, lest people be left behind. Not to mention, a big part of one mission is a non-optional mercy objective to kidnap/rescue the enemy's children, since you're leaving behind the other colony to die.
Many battles in Final Fantasy Tactics just require defeating one specific enemy. If you can do that, even if you're down to your last man and the next enemy barrage will definitely kill him, you automatically win.
In Final Fantasy Tactics A2 you have to follow the judge's rule for the match to get bonuses and sometimes to win at all, but since it doesn't acknowledge a law being broken until the turn it was broken on ends you can break the law without penalty as long as you end the fight on that turn.
The game also has multiple kinds of win conditions, depending on the battle. Some fights force you to endure waves of enemies for certain amount of rounds while others require you to weaken a specific enemy. Satisfying the win condition is all you need to do and nothing else matters.
Likewise in all three Luminous Arc games, where defeating XXX is enough to grant you the victory even if you have just one party member left.
Subverted in two late-game boss battles in Luminous Arc 3, however, where defeating the target without defeating a certain other enemy/enemies on the battlefield would lock you out of the good ending.
Rise of Nations declared victory if you were holding enough territory. So, even if there was all-out war and the balance of power was constantly shifting, if you could keep just enough land for a few minutes (or had the Wonder building that meant instant assimilation), you won immediately.
If you have the "World Government" (at the end of the Civics tree) tech online, you can skip the several minutes of waiting, bomb a few convenient targets, and then snatch them. World Gov skips the timers entirely.
Or if you build enough Wonders to get enough Wonder Points. Apparently you can conquer the world with art.
In the Rise of Nations Conquer the World campaigns you can purchase a territory adjacent to another nation's capital which grants you an army, then attack the capital immediately afterwards. If you win, you get the money back and every territory that nation had before you do this!
Seize missions in Fire Emblem have the objective of capturing the throne. If you do this, the level is cleared and all the enemies that might have been chasing you will just decide you aren't worth the trouble any more. Smart players will kill everyone for the EXP first, though.
Similarly, "Defeat Boss" missions end the moment the boss's HP hits 0. Great for speed runs.
Then there are the "Defend the Throne/NPC" missions, off course when the designated amount of turns over a handful of Redshirts appear and scare the enemy off.
In many of these missions, should the player manage to defeat the Boss(es) of the map and/or rout the entire field, the player automatically wins and the mission ends, even if this particular condition wasn't mentioned. It's still smarter to let the turns run out and milk the mooks for EXP, gold, and items though.
In EarthBound, if one of your characters has taken "mortal damage", you still have a chance to finish the battle before he collapses. In fact, all damage to your characters is applied by having your HP steadily decrease, and the higher your "guts" value, the slower it goes. Which is quite handy when one of the enemies explodes on death: you'd better kill him last.
The Advance Wars series loves this one. Aside from the HQ Capture method of victory (particularly important in AW1's "Advanced Campaign", where the enemy have overwhelming numbers and you're basically using all your units as sacrifices and bodyguards for one Infantry-loaded APC), many, many campaign missions from Black Hole Rising onwards have you winning by destroying the enemy's superweapon du jour (unit-spawning factories, big cannons, thing that heals a lot of units at once, sometimes all three), causing them to retreat and giving you victory even when their conventional forces overwhelm you.
Battalion Wars was pretty fond of it too. Certain levels basically end in the player trying to buy enough time to raise a flag.
Warhammer 40000: Dawn of War has this in the "Control Area" and "Take and Hold" victory conditions. The former involves holding over two-thirds of the Strategic Points, while the latter involves holding half of the harder-to-defend Critical Locations, but in both cases the idea is the same - if the timer runs down to zero, victory is achieved regardless of who has the bigger and stronger army.
The reverse is now possible in Dawn of War 2. While most games are based on holding points, it is possible to destroy the enemy base before the points all tick away, allowing an outmaneuvered player a (very difficult) alternate win condition. Note that it's mostly difficult because of the toughness of the bases; even with a few heavy tanks and the personification of the god of murder beating down on one, it takes nearly two minutes to destroy an undefended base, which is an eternity in a game whose rounds typically last 10 minutes or less.
Perhaps the most outrageous example is the siege of the Space Marine stronghold by the Tau in the Dark Crusade. The objective is to destroy their main Town Hall. Since the Tau Commander, if properly upgraded, is an invisible, jet-packed one-man-tank, he can cut the "sieging" and "storming" parts, sneak to the enemy base and raze the building single-handedly from a vantage point. That's it. One building. And despite that the whole SM army is still intact they will let out a mighty BAWWWWWWWWWW, admit defeat, and barrage their own positions with orbital bombing so that they don't fall in your hands. Suckers.
The same happens when playing Necrons vs Imperial Guard or, if harder to pull off, Space Marines. All you need to do is destroy the Imperial HQ, but access is blocked due to a large river. Conveniently there are some small patches of land and your Necron Lord can teleport. Better yet, he resurrects wherever he is slain and topping even that he can become an immortal Death God for a short while. So you teleport, kill the enemy HQ to death and go elsewhere to kill stuff.
Much like Fire Emblem above, victory is pretty much instantaneous in Battle for Wesnoth when you kill all of the enemy leaders, which can get pretty intense when you're struggling against a (money draining) turn limit and trying to farm as much XP as possible.
In the Hitman series, when you get to the escape point for a level, you're home free, even if there were a million cops and security guards shooting at you at the time. On some levels, this is partially justified (because the escape route is an airplane or helicopter or whatever and the level is otherwise isolated / difficult to chase you from); in others... not so much.
Even if PC was not discovered, the stealth rating drops when any alarm is raised. Of course, eventually any dead or unconscious body will be found, or knocked out NPC will wake up and run screaming, but it's not your problem if the mission ends one second before that.
Warcraft III has the custom map Defense of the Ancients: All-Stars: Destroying the World Tree or Frozen Throne is all that counts. It does not matter how many times the enemy Heroes get killed if they succeed in bringing down your main building. Kills and gold help, but if you happen to get a carry into the enemy base while they aren't looking, good game. Balanced in that you have to destroy all buildings in at least one lane before you can kill the Nexus.
The campaign itself had a few of those situations as well, of course.
Not to mention that even if you have enough resources to build 100 bases consisting of all the available buildings, have enough workers to do so 10 at a time, and your army is fully teched with three Level 10 Heroes (and is unstoppable compared to the opponent's), you will lose once all buildings go down. As a result, some players mass Siege Engines or Raiders and send them to sick on the enemy's bases in an "all or nothing" attack.
In the Dynasty Warriors series, defeating the enemy commander has this effect. Your own army can be utterly demoralized, all allied officers dead, and your commander on his last legs, but as long as the enemy commander goes down first, you score a win. Very useful if playing the commander.
Averted in Warriors Orochi. If you choose a character who's the commander for the stage, the game will usually generate an elite Mook as a replacement. If that Mook dies, you lose.
The Elder Scrolls IV Oblivion has gates to the hell dimension of Oblivion opening everywhere. The Oblivion worlds are full of enemies, but the best way to win is just to make a break directly to the top of the large tower and grab the Sigil Stone.
Which makes sense, because a portal to Oblivion collapses completely once its Sigil Stone is removed, and the player character and any of his or her friends will end up safely on the grass where they originally entered the portal. The daedra that were in that area of Oblivion, no longer have a means of getting from their world to ours and are thus no longer a threat.
Similarly, the final mission requires you to escort Martin Septim to the Temple of the One during a huge demonic invasion. To win, all you have to do is get yourself inside while Martin is alive. Even if he's a whole block behind you and surrounded by enemies, he will enter the Temple as soon as you do, triggering the ending sequence.
In fact, utilizing Good Bad Bugs, it's possible to trigger the end sequence in this way without ever meeting Martin Septim in the first place.
The same can be said about many four and five-star "Civilian Displacement" missions in Fable II. As long as you don't stick around and fight, the baddies won't stick around, either.
Due to the "war score" mechanic, almost every game Paradox Interactive makes has this to one degree or another. It doesn't matter whether or not the enemy has a force that can pummel you into the ground if brought fully to bear (or even if the majority of your army is wiped out); if you can seize an early lead in the war by taking provinces quickly, you'll often come out better off at the peace table than you were before.
At least the newer EU III versions work differently, countries consider whether they have armies left to fight. Which can lead to silly situations itself - a huge army will mean that your enemy may not surrender, even if you, e.g., control all of Spain, but Spain has still a huge army on Mallorca, though without any ships to move them.
Age Of Mythology has a particularly funny example in the expansion: as an invincible Titan wreaks havoc in the nearby city, the player's forces and an ally have to survive against the Titan's offspawns and other enemies. In the end, the Titan comes for the player, likely crushing his entire base...but as long as the player fulfills the objective of bringing 3 Rocs (Egyptian Myth units that act as air transports) to the ally, everything is fine and dandy.
Another example from the original campaign is a Tug of War mission. When the cart that is being fought over nears the players base, the enemy starts pumping out lots of units from his base... but they give up the second the gates close behind the cart.
Justified by game mechanics. In AoM, only your own or allied forces can pass through an intact gate of yours, even if the gate on-screen is wide open and enemies want to get in. Still funny to see though.
This can happen in Castle Risk, a rather less well-known variant of the popular board game Risk. Each player has a capital territory ("castle"), and if you lose that, you're eliminated from the game. Doesn't matter whether or not you're actually stronger...
Almost literally in Ico: you can try to beat the Shadows into submission with your length of wood, but bringing Yorda to the stone gates will prompt her to open them —which instantly dispels all Shadows from the area.
In the Wing Commander games, it's not always necessary to kill every last enemy to win the mission du jour. In fact, in a few missions you get chewed out for killing enemies if they're not to be destroyed.
This is quite common for the strike missions, particularly against the Kilrathi starbase at the end of Wing Commander I.
You can do this in Secret Missions. Plot a course straight for the Sivar, afterburn towards it and after wasting it get out of dodge. Only need to worry about a few fighters around the Tiger Claw.
Wasting men and resources to just kill enemies even if you don't need to do so to achieve the objective would get you chewed out in a real military, whatever video games might lead you to believe.
The plot of Wing Commander III has assigns the player to a outdated carrier taking part in various missions while The confederation is slowly losing the war while bigger ships fight in more important battles. Cue the development of Confed Secret Projects, which can end the war instantly if they can get to the right strategic location. Naturally, The final missions of the game has Commander Blair sneaking onto the Kilrath capital world with a small strike force to deliver a lethal blow and end the war that's been going on over 50 years (and 3 wing commander titles).
In Counter-Strike, Counter-Terrorists can win a round in hostage maps by rescuing all of the living hostages on the map. The key word here is living. If things got hairy, you could (as a CT) rescue just one hostage (out of 4 or 5, depending on the map) and let the rest die in the crossfire (or if you are truly sadistic, to off them yourself). Once that happens, the CTs will win the round for rescuing all the living hostages.
Terrorist teams often counter this "strategy" by offing all of the hostages at the beginning of the round, turning the round into a deathmatch - though many servers will auto-kick players for killing too many hostages.
Justified in bomb defusal (DE) maps, where the being set and going off before it can be deactivated counts as a terrorist victory even if their entire team is dead. After all, most terrorists don't care what happens to them after they successfully bomb something in real life, so...
World Of Warcraft has this in Wrath of the Lich King. In the Halls of Stones instance, there is a gauntlet called the Tribunal of Ages, where you have to protect Brann Bronzebeard from getting roflstomped by mecha-dwarves as he's tinkering away at the security system. You have to live for 5-7 minutes of constant mobs, that spawn faster and faster and even avoid huge purple bombs of pain and a laser beam. When all of these at once, you can be seconds from achieving victory, have all of your party members die, and yet you still win if Brann manages to subdue the security system and use them to destroy the mecha-dwarves.
Alterac Valley and Isle of Conquest battlegrounds may also count. The enemy might be swarming your base, attacking your general, but as long as your team manages to kill their general even a split second before yours dies, you win.
There's also Wintergrasp, where every 2.5 hours the attacking team has 30 minutes to storm the defenders' keep at the north end of the zone. If the attackers break through the three layers of walls and reach the sphere at the center within the time limit, they instantly win. But at the south end of the zone are three towers; if the defenders destroy all of them, they gain a hefty damage boost and 10 minutes are shaved off the attackers' clock. If there are less than ten minutes left, the defenders get an Instant Win.
Metal Gear Solid: Portable Ops has this in spades. For the most part, it doesn't matter at all if you're detected, as long as you get your ass to the checkpoint, you win.
In Mega Man X2, the battle with Agile takes place in a room with Spikes of Doom in the bottom, but if you kill him while in midair on top of them, you won't die when you fall on top of them afterwards. This is the easiest to accomplish by performing a Shoryuken on him.
The first game also had a boss with a spike pit at the bottom, but in that case, the spikes instantly crumbled as soon as you dealt the final blow.
A minor variation occurs in the Mega Man Battle Network and Mega Man Star Force games: When the last enemy on the battlefield is defeated, you lose control of Mega Man during the victory fanfare and are invincible during that time, even if a time bomb explodes a split-second after the last enemy is taken out. Up through Star Force 2, projectiles and bombs would remain on the battlefield in the background of the victory screen, but you'd still be immune to them. However, winning a battle by the skin of your teeth reduces your reward for victory, and in extreme cases will replace your reward with a mercy HP refill.
In Touhou games, draining a boss's health enough to make her move onto her next attack pattern will cause all bullets from the current attack to turn into items. The same applies to all on-screen enemy bullets upon reaching a boss. Earlier games would also give you a brief moment of invincibility during the explosion animation at the end of each boss's last Spell Card, though this was removed starting with Mountain of Faith, making it possible to die after beating the final boss.
Valkyria Chronicles uses this. Most missions are won if you seize the enemy's main base. A fun strategy is just running a scout into the base, grenading any troops there, and winning, regardless of the (likely rather poor) tactical situation the rest of your army is in.
In the Heroes of Might and Magic series, many missions can be won even after all the player's cities have been captured (which results in the player being given 7 days to capture one or face game over). The quickest strategy of completing Mandate of Heaven in Heroes of Might and Magic III is to take Castle Darkmoor, build it up as a Necropolis town, leave after getting a sufficiently large army and before the other factions take an interest in capturing it, then head to capture the Hive before the 7-day deadline results in game over.
In Lethal Enforcers 3, once you or your opponent reach the goal, the area ends, even if there are enemies still standing.
In Battle Stations Clan war, no matter how many members of the opposing team are able and willing to fight or how many defenders you've overrun, the battle is won when one side's fort is sunk.
In Age of Wonders, killing a faction's leader unit instantly defeats them. Many single player missions can be completed extremely quickly, simply by slapping haste on a powerful unit and rushing them to the enemy leader, completely bypassing the entire map covered in enemy units. On the other hand, it also makes it ridiculously easy to lose if you aren't careful with your own leader.
In Age of Wonders 2 Wizards can respawn, so this must be repeated as many times as player has Wizard Towers. If you're threatened, it may give even greater incentive to build them than the main function (magical relay).
Ace Combat series has various missions where you need to gain a minimum number of points by destroying targets within the time limit. As long as you made the point limit, you could just survive till the time ran out and the mission would be accomplished... if there is no "Mission Update". Some other missions you could just go for the targets and ignore the other enemies to win.
But also a subversion; there's a brief period of time between "Mission Accomplished" and actually completing the mission to be taken to the results screen, and during this time you can still crash into things and fail the mission. Ace Combat 2 had a double subversion, though, as a mission accomplished was still a mission accomplished even if you crashed and the only cost was a deduction from the cash. Missions in which a post-mission accomplished crash would be unavoidable normally (such as the obligatory canyon mission) just had the player immediately de-spawn once the final target is destroyed.
Air Force Delta Strike has several of these. One particular stand-out is the canyon mission with the steam-rollers, fly through the gate at the end and it ceases to matter how much health your plane has when you crossed that magical threshold.
Team Fortress 2. In the final moments of control point and payload matches, the pushing team is often outnumbered, surrounded, and dying left and right. But once the objective is complete, all opposing players are disarmed and fall prey to those they had been killing just seconds before. Taken to the extreme, one side could be losing the fight badly and still win if someone sneaks by enemy lines.
In fact, the Spy and Scout have achievements for doing so.
As a matter of fact, this happens quite often on Dustbowl. The second capture point in each part falls extremely quickly to a spy or scout sneaking past the defenders if they get too bold and fight too far away from it.
It actually is one of the three common win strategies: 1. Steam roll 2. Lots of teamwork 3. Spy/Scout Capture
Inverted against the player in Mann Vs Machine mode. It doesn't matter how badly you're steamrolling the robots' spawn point, if a single Scoutbot sneaks behind you with the bomb, you're done for.
The humans do still have an instant-win condition against the robots, just one that's tough to exploit. If, for example, a wave consists of 30 Soldier bots and unlimited "support" Scoutbots, killing the 30th Soldier bot causes the Scoutbots to drop dead instantly, no matter how much of the field the Scoutbots control.
In Freelancer, it is mentioned near the end of the game that Rheinland forces have pretty much obliterated most Kusari resistance and have almost conquered the House. However, once you win the game, everything returns to normal and the Rheinlanders go home. This is, however, justified in that the Rheinlanders were under the control of the alien Nomads, and once the Nomads were defeated by Trent's activation of the hypergate, their control broke.
In Z, the objective was to destroy the opponent's fortress by a) direct assault b) destroying all of the enemy robots or c) getting a unit inside the enemy fort. You could have a strong army and most of the map claimed, but it's all for nothing if a bunch of snipers sneak past your defenses, take out the turrets on your fort, and casually stroll in.
In the first few missions in Thief, if you're playing on the easiest difficulty, the mission ends a few seconds after you finish the objectives - you don't need to escape from the place you're robbing. This has some absurd consequences: for example, in mission 3, "Down in the Bonehoard", if you time it right, you can grab the MacGuffin, then jump down a very deep pit... and somehow survive, since the mission ends in victory before you can reach the bottom and die.
In the Total War games, when assaulting an enemy settlement, you win by either destroying the entire enemy army or by holding the settlement's central plaza for a certain amount of time (which generally translates to having at least one of your guys within the plaza's boundaries and no enemies). Even if there's a ginormous enemy reinforcement army approaching, you will still win as long as it fails to reach the plaza in time to disrupt the timer. This can make for some Awesome, if rather cheap, victories.
Standard battles also have timers. It is entirely possible to have a single unit of some kind left during a snow/rainstorm hide out waaaay at the corner of the map, and win due to time out. (In clear weather it's simple enough to just search the forests then the corners, but in snow/rain visibility falls to nothing and so long as you turn off the AI engagement the enemy can walk right by you and not notice you.) In campaign, this only works on defense.
The armies remain, though, as Rebels. You still have to deal with them.
X Moto is a 2D moto racing game where you need to avoid touching wreckers or touching walls with your head. Most levels are user-contributed.. and the default game rules play the trope straight.
Some levels play it too straight to the extent of lampshading - like a "Jump to Death" level where you can save time by doing an unsurvivable jump with a slim chance of touching level goal before dying.
Some levels avert the trope by setting alternative victory condition of "having done X" where check for "X is done" is only performed when you are in relative safety.
Some levels subvert the trope by making teleports that look like level goal.. It is not too dishonest - these points usually have to be reached anyway, but going headlong down the cliff doesn't work here.
Trackmania titles do the same thing. Your time is recorded when you reach the finish, even though the track ends there and you usually fly off into oblivion or faceplant something solid immediately after crossing the finish line. Some track builders purposely place a ramp or obstacle there to make the inevitable post-finish crash all the more spectacular.
Averted in Indestructo Tank flash game. You want to get a high combo by hitting a lot of enemies without landing. But you have to land for the accumulated score to be accounted for - and for the fuel to be replenished. So you can die if your combo went too well.
In Call of Duty: Modern Warfare 2, a player that gets a 25 man kill streak can call down a Tactical Nuke onto the map, which instantly wins the rounds for his team. This happens even if the rest of his team are complete bullet sponges, and would otherwise lose the round collectively.
The Cavern of Transcendence trial in City of Heroes becomes incredibly easier if you have a teleporter who also has stealth. You have 90 minutes to complete the mission, much of it taken up fighting your way through tunnels to the door of the cavern, then a huge roomful of monsters between the door and the eight obelisks that have to be clicked at the same time. A stealth porter can get quickly through the tunnels to the door and then teleport the team. Once inside the chamber, the porter can then run to each obelisk and teleport a team member to it. Once they are clicked simultaneously, trial over, go team! It's entirely possible to complete the entire thing without having to engage in any combat, and often then only if a spawn of monsters is too close to the cavern door when you enter to allow the team to wait for the porter to do his thing.
This is even easier in City of Villains, as Stalkers have access to Hide at level one. In most non Escort Missions, you only have to clear out the last room, and even then that's only for newspaper missions. It's balanced out a bit by the fact that ambushes can see through Hide... while escorts can't.
Sonic the Hedgehog (2006). In Crisis City, Sonic is being chased by a tornado made of fire, yet hitting the end of the level causes Sonic to stop and do his victory pose while his score tallies. As this happens, the aforementioned tornado is still visible in the background, and it just stops chasing Sonic for no discernible reason. "I don't feel like chasing you any more."
Sonic Adventure 2: When fighting The Egg Golem as Eggman, it's possible to kill the Golem while falling to your death in quicksand.
Possible in Rock Band; all you have to do to pass a song is finish it, but if somebody fails out, the band has to save them within a reasonable window of time or everyone fails. This can happen twice, and the third time is an inevitable band failure... unless it happens close enough to the end for the song to complete (including the second or two it takes to transition from the song's end to the score screen) before that.
Blatantly obvious when a Big Rock Ending is involved, as the moment the Big Rock Ending hits, EVERYONE that was failed out is revived and the performance meter is removed.
Also obvious in any song in the older games (Rock Band 2 and earlier), where the crowd would boo your band loudly, until you hit the invisible point that ended the song (which is usually well after the last actual note of the song). Then they would suddenly switch to cheering.
In Scribblenauts you'll frequently watch Maxwell go through his death animation or disappear down a bottomless pit, but it's alright, because he touched the Starite before dying, so the victory screen pops up.
It gets even better in one of the puzzle levels of world 4: You have to destroy everything to make the Starite appear, but you can also just use a nuke or something similar and hope to touch the Starite before losing the level.
Age Of Empires III: I don't care if Washington is incapable of fighting, my only unit left is a villager, the entire Colonial militia was destroyed, the enemy is closing in on the camp at Princeton, or if I bankrupted the Revolution's fight in Trenton, those petards destroyed the enemy capital!
Similarly, in the steal-the-spanish-treasure-fleet mission, the Spanish can't take ships back, so it's entirely possible, having five of the six ships required, to win with a tiny army even if the Spanish have destroyed your colony entirely.
A lot of Mass Effect 2 fights against major enemies (not simply bigger enemies, but strong enemies that are part of the plot) will include many other enemies that you can forget about. The moment the major enemy is killed, the battle is over.
Also, on the final mission when you have to escort a tech expert through a series of pipes. Hitting the last switch in the mission ends it instantly (triggering a cutscene). Regardless of how many enemies are still present.
Battle Isle. If you manage to sneak an infantry unit into the enemy's base, you win regardless of how much troops each side has remaining. And, of course, vice versa. In some scenarios, this is the only feasible way to win.
Jump Man. The goal is to collect all bombs in a stage. Even a small fall will cause you to plummet to the bottom of the screen and die on impact, except if this plummet happens to pass through the last bomb; this counts as a stage victory.
Likewise, in Spiritual SequelHap Hazard, collecting the last bomb will end the level with a victory. Doing so also adds two seconds to your clock, which is absolutely necessary in order to complete the game within the time limit (not that this is specified in-game anywhere).
In The Bugs Bunny Crazy Castle, in both the NES and Game Boy versions, if an enemy kills Bugs, he can still beat the level with no penalty if his death animation collides with the final carrot of the level.
One of the early Terran levels in Starcraft requires you to survive for a set amount of time. You can still win even if all you're completely overrun and all your units and headquarters are destroyed, as long as you take one random building and fly it to the corner of the map.
There are also three missions where, after satisfying the instant win condition, you get to bypass the mostly intact Protoss base between your forces and the artifact fragment. On two of these, this is the most likely way to finish the mission.
Collecting the last star in Glider PRO makes you a winner, even if something else kills you at the same time.
In the original Defender Of The Crown, you win if you take the three Norman castles; no other castles or territories are required. Although it's rare, it's possible to win with one or even both Saxons still alive, even though they're supposedly fighting for the crown just like you. If another saxon win this way, you get a different "Game Over" message then the usual one. If you get defeated, you get a message about how you flee and vow to return one day. If another saxon wins, you get a message about how the new king sends you as a diplomat to some boring place.
In Net Storm: Islands at War, the objective is to immobilize the opponent's High Priest, capture him with a transport unit and bring him back to your island to be sacrificed. While doing so, the only units that must survive are your own High Priest and the transport while carrying the enemy priest, and the only building that must remain standing is the sacrificial altar.
A mission is only finished in Alien Swarm when all surviving marines are in the exit area. Whether they're on fire, parasited, surrounded by shield bugs or up to their knees in swarm.
In most fighting games, once your opponent hits 0 life, any attacks still on screen are nullified. (In some games, you can be killed by on-screen attacks, in which case the round is a double KO.)
In Homeworld each side owns a single Mothership and the Instant-Win Condition is to destroy the enemy one. Whether it happens a mere second before the enemy fleet destroys your Mothership doesn't matter.
There is an Aztec mission in the Age Of Empires II expansion, The Conquerors, where you have to destroy the wonder in Tenochtitlan which the Spanish are somehow using to control the Aztec populace. It is possible, at least on lower difficulties, to gather all your starting units, ignore any and all enemy attacks, and march straight up to it and destroy it. You win the mission when that happens, never mind that your tiny force is surrounded in a large, well-garrisoned enemy city.
In Zork Zero, the Double Fannucci minigame can be won instantly if you undertrump three cards after your opponent discards a trebled fromp. This effectively the only way to win, seeing as the rules of this card game are never explicitly stated and are just about impossible to derive from context (intentionally).
In Resident Evil 5 When fighting against both Wesker and Jill Valentine, all you have to do is survive for 10 minutes. Even if your on the cusp of death, once those 10 minutes go by, Wesker leaves. You still have to break Jill out of her mind controlled state, but that's easier than fighting a guy who CAN DODGE A SHOTGUN SHOT TO THE FACE POINT BLANK RANGE.
Subverted in the Inazuma Eleven series' mini-battles. If a player shoots at the goal and makes it in, the goal counts and can affect the win condition as long as the shoot animationnote or more precisely, the fade out before the fade in to the close-up for the shoot animation started before the countdown hit zero. As a result, if a mini-battle tasks you with defending for a set amount of time to without letting the other team score a single point, and an opponent shoots at the goal but time runs out while the ball is in mid-air, you still lose if the ball makes it in the goal.
An interesting version occurs in the time travel RTS Achron. One of the main win conditions for multiplayer maps is you win if all attack and build capable enemy units are destroyed at any point in time at or before the present and the other win condition is if that destruction falls off the timeline (becoming permanent). If the latter win condition is used then there is no way for the opponent to change what's happened because the events have become permanent but if the former is used you can win in the present even if your whole base has been destroyed in the past.
Aerobiz: Regardless of size or overall passenger totals, the first airline to meet all the goals, wins. This can lead to some odd situations where a large airline, dominating the passenger totals, profits by big margins, loses to a much smaller airline that happen to dominate their home region and expand into three otherwise ignored regions.
In the Razor Rendezvous mission of Rogue Squadron II, the mission is automatically completed once the Star Destroyer is destroyed even if you did so by crashing into the bridge Arvel Crynyd style.
One of the victories in a standard World Of Tanks random battle is capturing the enemy base. Even if you are alone in capturing, most or all of your team is dead, you have one hit point left, as long as you are in their base for the required time, you win, even if there is no way you could possibly hold the base.
In Bridge Builder Series games, if the last vehicle reaches its destination, the level is completed, regardless if the bridge was single-use only.
Grim Grimoire: You can theoretically end the Hold the Line missions early by destroying enemy runes, but this becomes practically impossible in higher difficulties.
In single player mode of Mario Party 9, you go against either one or two AI characters on the board and losing to them is an instant loss to you, even if you finish in 2nd. However, some boards put you with one or two friendly AI characters and if those characters win the game instead of the evil characters, you still clear the board, even though you didn't win.
In The Godfather 2, an enemy Family is defeated once you take over their Compound. There will be no Remnant running around trying to take back territory, unlike the first game; all will be Killed Off for Real even if you did not use the kill conditions. Balanced in that you need to take all their fronts first to unlock the Compounds.
In the NES classic Bionic Commando, stages are considered completed when the reactor is destroyed. Doesn't matter if you're swarmed by enemy soldiers, a huge guard drone is bearing down on you, or a cyborg soldier is slapping you around with his own grappling hook; shoot out the power core and the level is won, with all defenders disappearing upon its destruction.
Surgeon Simulator 2013 does this with impunity. Ribs completely shattered? Lungs on the floor? Stomach detached? Down to double digits of blood left? It's instant victory when you slap the replacement heart in the patient's chest!
jubeat has a variation of this. Once you hit 700,000 points (out of 1 million), you've cleared the song, though the song will keep going to the end. If you really want to, you can goof off or rest once you hit 700k rather than aiming for a higher score.
Often occurs in Warhammer 40000 in missions where the objective is to hold more strategic locations than the enemy. You only need one troop to hold the location, so often the game ends up being determined by some small squad holding an objective far from the main battle.
Although this is more of just a win condition, not an Instant Win Condition. Completely tabling your opponent means that you win, regardless of whether the game was supposed to be about capturing objectives.
However this can lead to the quite possible situation where the last two remaining models on the board simultaneously kill each other, resulting in both players instantly winning.
And that, good sir, is called a draw.
Also, a popular tactic in objective games is to have your most mobile units charge forward at the last second to contest enemy-held objectives. Since contesting an objective denies your opponent an extra point, it is possible for you to win, even if what's left of your army is about to be wiped off the table.
Thanks to Kill Points, your whole army can be wiped out but still win as the other player was using an horde army that had twenty kill points compared to your five (you know this to be true, Guard players).
Not strictly true - it's stated that the complete extermination of one side is considered a victory by the only side to still have people on the field.
6th Edition has introduced the Absent Forces rule - if one player has no models on the board at the end of the Game turn (rather than their own personal part of the turn), they instantly lose. Against an army that makes heavy use of Deep Striking, Outflanking or Reserves, where a random number of units will appear in the first turn, it's possible that only a small number turn up and are quickly exterminated, or - as in one very famous example - are prevented from entering play at all.
Warhammer Fantasy can have this too, in regard to the Vampire Counts and Tomb Kings. Being undead, the army is held together by the will of it's general (or Hierophant with Tomb Kings). As a result, if the general is killed, the army begins to fall apart at that exact instant and at the beginning of each turn after. As a result, if you can kill the (usually heavily guarded and well protected) general, you can gain such an absurdly huge advantage that, even if your opponent is in an amazing position, you can still win. And if the Vampire Counts or Tomb Kings player is in a poor position when the general falls, they usually just surrender.
The concept of "racing" is when each player just attacks with their creatures and doesn't block for any number of reasons.
Magic has cards that change the victory condition, allowing you to do this. There is one card that lets you win if it is the only card you have in play and you have no cards in your hand. Play it at the last second and a curb-stomp victory for the other guy can be snatched away by non-linear planning.
Other conditions from other cards include but are not limited to: Having 50 or more life, having 200 or more cards in your library, winning 10 coin flips, controlling 20 or more creatures, having 20 or more cards in your graveyard, having a land of each basic land type and a creature of each color, having exactly 1 life remaining, or keeping a card on the board long enough to put 5 filibuster counters on it.
Then there's the flip side, cards that instantly cause someone to lose the game. Doorway to Nothingness is an example, in that it will (if you're able to satisfy its very high mana cost) instantly cause someone to lose the game. Phage the Untouchable is another example, in that if she deals combat damage to a player, they lose. There are also the creatures that give players poison counters, and a player has 10 poison counters they lose. Finally,a planeswalker introduced in Return to Ravnica, Vraska the Unseen's ultimate ability creates 3 1/1 assassins that if they hit a player for damage, that player loses the game.
Many infinite combo decks win by sacrificing large amounts of life, cards in deck, cards in hand, or cards on the board in order to set up a winning game state. The first famous (as in, dominating a full season of tournaments) combo deck, Pros-Bloom, went so far as to go down to a negative life total before fatally draining the opponent. This was only possible with the rules at the time.
One of the early combos, the ChannelBall, is also a Disc One Nuke. If you have the following cards in your starting hand, you can win the game in your first turn: Mountain, Black Lotus, Channel and Fireball. When performed successfully, you're left with one hitpoint.
Of course, if the other guy has a Force of Will (a counterspell which can be cast without mana), you're pretty much hosed.
Another combo involved spells that you had to pay for next turn; if you didn't, you'd lose the game. The deck would play more of these than they could hope to pay for, then use the benefits of those spells to win before the next turn ever started.
Similar decks would play the same spells and force the opponent to cast them somehow. Depending on the deck and spell, it would often be impossible for your opponent to pay the cost for even one of them, let alone many.
Cards have actually been designed around this trope, the most explicit being Final Fortune. The card's effect: "Take an extra turn after this one. At the end of that turn, you lose the game." The nearly identical card Last Chance has the helpful reminder text "You don't lose if you've already won".
"Decking", the original alternate win condition: If you're told to draw from an empty library, you lose. This is harder to do than getting your life to 0, though, so it's rarer to end a game by decking.
Unless you've deliberately set up your deck to "mill" the opponent into submission. Cards such as Millstone, Halimar Excavator, Rise of the Eldrazi's Keening Stone and any other Ally card are all useful unless your opponent has a card that allows them to shuffle their graveyard back into their hand. (Even if they do, the original Feldon's Cane has to be exiled from the game after use, and the fancy mythic rare Eldrazi that can do this for free are, well, mythic rare.)
Also, there's a card from Innistrad, Laboratory Maniac, that turns the instant lose condition into an instant win condition. If you would lose the game by being "decked" with the Maniac out, you win instead.
A rather hilarious combo uses Ashnod's Coupon, a joke card that says "Target player gets you target drink. You pay any costs for the drink." to force your opponent to either surrender or give you an obscene amount of Real Life money. First you use a card to switch Ashnod's Coupon to being under your opponent's control. Then you play a card that allows you to take their turn for them. Force them to activate Ashnod's Coupon, targeting a drink you brought with you. Since it's your drink, you can name your own price for it. All you have to do is make it a price your opponent wouldn't pay.
The Yu-Gi-Oh! Card Game loves this. The Cyber Dragon era of the card game consisted of gambling that your one attack would go through, and win the duel. Of course, more advanced players would only do that after getting rid of potential traps with the card Heavy Storm.
An interesting twist are a series of illegal cards that state that, when used to end the duel, you win not only the duel but the entire match (typically best 2 out of 3)
Yu-Gi-Oh's specific win-condition cards include: Successfully inflicting damage with "Vennominaga the Deity of Poisonous Snakes" three times (but it's tricky enough to summon), "Final Countdown," a stall victory condition that activates after 20 turns, a faster victory condition called "Destiny Board" which nonetheless requires stalling and hoping your opponent can't remove the cards on your back row, the iconic getting all five pieces of Exodia in your hand, and the now-banned "Last Turn" which has one of your monsters and one of your opponent's of their choice duke it out for a last battle. When playing a match with someone, perhaps in a tournament, where the winner is determined by best of 3 games, the aptly named card "Victory Dragon" automatically wins you the entire match if you win just one game with it striking the finishing blow.
In addition, if you can create a chain so that you get a win condition before your opponent, their win condition seems to magically disappear - for example, activate Ring of Destruction when your opponent gets the last piece of Exodia or "Spirit Message - L", knock their Life Points to 0, and you win instead because chains resolve in reverse of the cards being activated. So your effect happens first, unless they can stop it.
There are also many decks based on stalling until the right cards are available in your hand for a sudden and usually completely unexpected turnaround win in one turn. An example of this is the "Armed Samurai Ben Kei" deck based on amassing field clearers like "Heavy Storm", "Giant Trunade", and "Dark Hole" as well as enough equip cards to reduce the opponent's life points by at least 8000 in one turn while exposed. Variations with other cards capable of this damage exist.
And in just about every CCG, you can cause a player to lose by fixing it so that they run out of cards in their deck before you do; if it's their turn to draw, and they can't draw any cards due to there being none left, they lose, no matter how far ahead they were at the time. This is referred to as "milling" in card game parlance.
An exception to these is Magi-nation, where, due to the nature of the game, games can last a very long time indeed, the rules indicate that when you run out of cards in your deck, you shuffle your discard pile, and set it as your deck. The only way to win is to have the opposing Magi hit 0 energy without any creatures on the field, so it's entirely possible for both players to lose if they aren't careful.
Milling was used to great effect with Durant in the Pokemon Trading Card Game, who has one very inexpensive move that forces the opponent to discard cards equal to the number of Durant on the player's side. It became enough of a problem that the card designers created a card designed specifically to get rid of Durant.
Lost World provides a victory if the opponent has 6 or more Pokémon in the Lost Zone (a super-discard area used in the Pokemon Diamond And Pearl era). This is not as difficult as it sounds: Gengar's "Catastrophe" effect sent knocked out Pokémon to the Lost Zone instead of the normal discard pile, and an evolved Pokémon sent there will also send all of its previous evolutionary forms there too. This meant that the player only needed as few as 2 knockouts to win the game using Gengar and Lost World.
This will result in many research centers, and a plummeting economy, but we'll be dead or Gods in thirty weeks, so what are the loan sharks going to do? Pray threateningly?
This resulted in a truly epic bungling of the game's economic system that stopped his research dead in its tracks. His victory was in spite of this funding idea. Basically, that player was a lucky idiot that time around. (Let's hope he learned from his mistakes.)
He did. His next game he's going for cultural victory (is it?), but several problems changed him to start liberally blowing up suns instead. Then he won a Alliance victory.
Jenna Casey, cornered after Sol was destroyed: "...While we know we cannot defeat you, we shall have the last laugh. We have surrendered to the Dominion of Korx!"
Long story short, as long as you manage to research the technology victory in time, you win even if every single planet you own is a turn away from being blown up.
Chrononauts has three separate ways to win: alter the timeline in the right ways, fulfill your mission by collecting a certain combination of three artifacts, or have ten cards in your hand at the end of your turn.
Fluxx, from the same developers, can have up to two victory conditions, depending on the cards in play, and they may or may not be mutually exclusive. Sold separately are packs of blank cards that allow people to make up cards which could do this.
We Didn't Playtest This At All is made of this trope. For an example, here are a few ways you can win by playing a single card: Being the only girl, being the only one without points, having an even number of players in the game, having five or more cards, owning a pony... The game works by stint of it being possible for anyone to win at any time, and all players accepting that the game will, probably, only take a few minutes to play.
The BYOND Game Space Station 13 subverts this by having the victory conditions be to get onto an escape shuttle. Even if the station is about to explode, any crew on the shuttle when it leaves win the game. Played straight in Traitor mode sometimes, because of the objectives. You can be on the shuttle, surrounded by security officers and high personnel with tasers, and (if the objective doesn't require solitary escape) you will win the round when the shuttle leaves.
If the entire nuke team (usually 3-5 people) or the wizard dies, the crew instantly wins. Even if they use the 'suicide' verb.
Games with a timer to survive work like this, including some Tower Defense games (Lock's Quest even made it a sort of plot point). You can be surrounded by mooks who have destroyed your defenses and are about to overrun, but if the time runs out and you're still alive, you win!
The original Lord of the Rings collectible card game. You win by having the most points after a certain amount of time - but if you manage to destroy The One Ring, you win immediately, regardless of score.
And, for that matter, the newer game (based more on the films). As long as your ringbearer survives all skirmishes at site 9, you win, even if he's an inch from death and the rest of the fellowship died turns ago.
The Legend of the Five Rings CCG was made of this trope. There were three victory conditions: Military (wipe out your opponent's territories), Honor (Gain a large amount of Honor points), or Enlightenment (play all 5 elemental rings). Some VERY Successful decks were designed around making a suicidal dash for max honor or enlightenment while paying just enough attention to the opponent's attacks to not be completely wiped out before winning.
The Eye Of Judgment has this built into the core rules. First person to get 5 creatures onto the field wins, period. So theoretically, you can win just by summoning weak weenie monsters onto the field, who can't even fight, as long as your opponent can't get rid of them fast enough. Or your opponent can have some super high cost death machine on the field and be ready to destroy your mons, but if you slam a 5th mon on the field, you win, period.
Of course, there are numerous ways to prevent such a strategy built into the rules. Monsters can't attack the turn they're summoned, and only deal damage first with a specific ability when attacked (if they're attacked first and wiped out, they don't get to counterattack, obviously), so summoning a weak monster in an indefensible position will get them killed. In addition, it costs mana to summon, attack and turn monsters (they can only attack in specific directions), and if you turn, you can't attack. The layers of strategy that go into a three-by-three board where the only requirement is getting five monsters on the board is immense.
Getting a rabbit to the back rank (or finishing the last of your opponent's) in Arimaa does this.
Pops up in official Dungeons & Dragons adventures from time to time; any group of adventurers worth their salt that ends up in a Bolivian Army Ending situation should immediately begin looking for the leader of a group (without which they'll break and run); the source of power; or the secret compartment leading to their goal. Of course this is usually up to GM discretion: the rules might *say* that an enemy force will break and run if more than 50% of their troops are killed, but if that number only gets to 51% because the pacifist cleric broke his vow and scored a critical hit while having 5 HP and defending the fallen bodies of his comrades, well, even kobolds aren't that dumb.
There are several alien powers in Cosmic Encounter that allow for new win conditions. Notable are the Masochist (win by having all your ships die), Sadist (win by destroying enough of your opponents' ships), Tick-Tock (win by having enough time pass) and Genius (win by having 20 cards in your hand). All of them can win by the standard method also, but they generally have no useful ability in game.
In Erfworld, the death of a side's leader will cause that side's entire population to Disband, provided they are out of heirs.
Most fighting sports are like this. If you knock out/pin your opponent or make him submit to you, you win right then and there and don't have to sweat out the judge's score cards. Though generally, the fighter who gets more points is doing a better job in the fight and more likely to KO/pin his opponent.
Pool has a couple versions. In Nine-ball pool if you pocket the 9 ball on any legal shot, you win regardless of how many other balls remain on the table. In Eight-ball if your opponent pockets the 8 ball before all of their other balls (or scratches while trying to pocket the 8), you win.
In the ancient (and unnamed) Mesoamerican Ball Game, you scored points by bouncing the ball against the opposing team's side of the stadium, but you could automatically win by knocking it into a tiny circle situated high up on the wall just barely large enough to fit the ball through. This would be humiliating enough if it weren't for the fact that their entire team was sacrified for losing the game.