It is obvious that the game is naturally over in RPGs when the party is defeated in battle and the story wouldn't go as planned.
However, in some games, the game simply ends if the main character themselves are killed off, even if the rest of the party is healthy enough to continue fighting. RPGs where you have to protect a key character also end if the said character gets killed, which is similar to an escort mission. It's an Instant-Win Condition for your enemies' benefit... Even if some of the characters still standing have White Magic or suitable Phlebotinum that would otherwise permit them to resurrect the fallen character.
More intuitively logical if the game is entirely from the main character's viewpoint. If so, then the game logically ends if the main character is killed, because their viewpoint dies with them. Likewise, the escort version can be justified if the main character's plans are riding on them, as their death would leave the heroes without a prayer. Also, many RPGs have a late game or final boss that is only vulnerable to a weapon or technique that only the main character can use, making the game unwinnable if they die.
This trope probably originates from chess on some level, if the King is in a position where he will be captured on the next turn and without any means of escape, the game is automatically over regardless of how many other pieces are in play.
For the military commander version of this trope, see Decapitated Army. For non-Video Game equivalent, see We Were Your Team.
<Hero> Must Survive is a gentler version, primarily in strategy games, that doesn't force you to risk the hero all the time.
Escort Mission is a sister trope where important NPCs dying will end the game. Compare Lazy Backup, where the game ends when the entire active party is defeated, even if other party members are healthy.
This should probably go without saying, but don't throw everything in here that ends a game if a character dies. The most important elements: there are others that are nearby and should be able to revive the character, and that the death or defeat in question is impermanent.
Averted in The Warriors to some extent. When your character is killed, your allies will attempt to revive you if you have any flash in your pockets. However, you will still get a game over if your allies are too far away or they take too long to save you. This can be adverted in co-op mode since the game won't end unless both players are dead for good, but if the surviving player cannot find flash to revive his partner with and gets to an area where all Warriors are needed to advance the level, the game becomes Unwinnable and forces the players to restart the level.
Super Smash Bros..Brawl also rides on this trope in the Subspace Emissary during co-op play. Both players share the same stock and characters and the game will go on if player 2 is out for the count, but god forbid that player 1 gets taken down, the game automatically ends, even if player 2 is alive and kicking.
When a player selects the Ice Climbers, he or she will control Popo as Nana trails behind. It's possible to kill them individually. Nana can get killed without it counting as a KO, but if Popo dies, Nana will also vanish into thin air. This applies to Melee as well.
Some of the Ice Climbers alternate colors swap Nana for Popo, inverting it. Basically, if the Ice Climber the player is directly controlling gets KOed, it counts for both of them.
Let's not forget Olimar in Brawl. If he hits any of the boundaries, his Pikmin automatically die.
In Dragon Ball Z: Hyper Dimension for the Super Famicom, this was incredibly prevalent in the story mode; when fighting with "secondary" heroes like Vegeta or Piccolo, those battles literally didn't matter. If Piccolo beats Freeza, the following cutscene has Piccolo complaining that he can't hurt Freeza; if Vegeta beats Cell, Cell simply "regenerates" in the following scene. And if either of them lost, the story mode simply continued. But if Goku loses? Time to continue!
First Person Shooter
Several squad-based first person shooters follow this trope as well. Oh sure, when your teammates catch a few too many bullets, they just get incapacitated, and you have to go save them. For you, however, it's straight to the morgue.
Medal of Honor: Pacific Assault handles this in a fairly believable fashion. Getting shot too many times will leave you on the ground bleeding, and your medic will have to come and treat you. If he can't get to you in time, various things happen to seal your fate...ranging from a Japanese soldier finishing the job and clubbing you in the head, to the voice of your drill instructor ranting at you for not being a good soldier before you finally expire. It has a surprisingly profound effect.
Kane And Lynch handles it in a mildly believable fashion - if a character is wounded badly enough to be knocked down and dying, they will have to be revived by one of the other members of the crew via an adrenaline shot before they bleed out. However, overdosing on adrenaline (too many shots in too short a period) ends the game as well. Voiceovers and flashbacks often occur during this period.
Army of Two allows the players to drag each other to safety and bandage each other up if they are wounded to the point of being nearly-dead. Usually accompanied by the wounded partner complaining about how incompetent the other is at medical work.
Gears of War only averts this in the two player mode - if a player is knocked down, he won't die unless someone puts a few more rounds into him, but the other player can come over and revive him. In single-player, though..
Notably averted in Gears of War 2. Since the computer now has the ability to revive you once you are incapacitated, single-player doesn't end if you are downed (very helpful in multiplayer as well, which now contains bots). However, in the sections of the story mode where the human players are separated, going Down but Not Out results in instant death, regardless of the fact that there's an NPC right there who could help you; that issue is also fixed in Gears of War 3.
Left 4 Dead uses this. If there are computer players in the game, the game ends when all human players are dead, regardless if the AI characters are alive and despite the player respawning later in the level. Through the use of some console commands (PC only), you can override this condition and have the bots finish the level if you and your friends are dead, possibly respawning in a closet if the bots can make it that far.
VS mode makes this trope extremely annoying if there any survivor bots on the team. If all human controlled survivors are killed, the round ends, despite any survivor bots being alive. Infected players who know of this exploit will focus their attacks only on the human controlled survivors.
Operation Flashpoint averts this. If you're killed, you simply die and the camera slowly pans across the battlefield as the NPCs continue on with the mission. In some cases, you can be killed in the opening shots of a battle and watch your remaining NPC squadmates successfully finish the mission without you.
The Rainbow Six Vegas games also subscribe to this trope. If one of your colleagues goes down, they can be healed within a few seconds; if you die, it's game over. That's why the vast majority of players send their subordinates in first.
Basically played straight in ANY entry in this series that doesn't allow you to directly control any of your teammates (as in you can't jump in their body and control them). In the entries where this is allowed, such as the PC versions of all the Rainbow Six games BEFORE the Vegas series, and even the GBA version of Rogue Spear, if the character you're controlling is downed, you'll automatically jump into another member of your team, averting this trope.
Justified in Killer7, where the characters are all personalities of the same man - if that man dies, he takes all six of the others with him.
In the SWAT series it's a mission failure if the squad leader (a.k.a. the player) is downed. If any of the other squad members are downed you just lose points. In SWAT 4 and potentially others you lose the same amount of points for getting slightly wounded as your allies getting severely wounded.
Halo: "Without the Captain, the Covenant have already won". Averted in 2 and 3, where major NPCs are given Gameplay Ally Immortality, and only die when the plot requires it.
Friendly NPCs sometimes reference this trope by name whenever the Chief dies during gameplay.
Hack And Slash
Even though you often have multiple characters to switch between in Drakengard 2, each with their own health bar, if any are defeated, the game ends.
Justified in the Dynasty Warriors: Gundam games. As the battle gauge (basically a measure of how many spare mobile suits remain) empties, your operator becomes increasingly worried about the dwindling resources and chances of victory. If the player is destroyed while the gauge is empty, that's taken as the sign to cut losses and evacuate.
You can actually abuse this trope to your advantage in some Dynasty Warriors and Samurai Warriors games. The designated leader of the clan is the lynchpin for both you and the enemy, and most of the time you're saddled with phenomenally stupid AI, so sometimes it's more beneficial to play as said clan head and be in control of your destiny. (Later games in the series, including the crossover Warriors Orochi, would just put clan control in the hands of a different NPC if you tried that trick.)
In Samurai Warriors: Chronicles, the series' first game to feature multiple playable characters for each battle, on top of any other conditions specific to the current mission it's an automatic loss no matter what if the protagonist is defeated.
In Super Robot Wars, any robot destroyed in battle, from the ones cobbled together out of the junk in someone's backyard to the greatest machines ever made by mankind plus at least one Sufficiently Advanced Aliens civilization, can be repaired after battle, for a price. Unless it happens to be a battle against their particular arch-nemesis, or they have to do something in a plot sequence during or after the battle. And of course, you need a place to repair them, so the destruction of any mothership is game over.
One installment features a particularly justified version - if you allow the Ideon to get to full power and then lose all its hit points, the game ends - not because you can't proceed without it, but because destroying a full-power Ideon has the unpleasant side effect of blowing up the universe.
In the very first SRW, units were handled like in Fire Emblem, if they get destroyed they're gone for good, unless of course you're lucky and you can get your leader to roll up a revival spell, and if your leader dies, you lose instantly, which is somewhat justified since your leader is the only one who can use spirit commands and is, well, the leader.
In the 'J' installment, any mission featuring the main antagonists - a race of hyperadvanced Crystal Robots AndLatex SpacesuitHuman Aliens who have slumbered in the heart of the moon - will end in an instant Game Over if your protagonist dies. Not because he/she cannot be recovered or repaired - that's no problem in the OTHER stages - but because the enemies possess a Time Stands Still superweapon, and the only thing capable of blocking it is your unique Humongous Mecha. So if you go down, they'll just stop time and wipe out the rest of your friends without breaking a sweat.
Front Mission doesn't seem to care what happens to characters critical to the plot of each mission, so long as Royd doesn't get blown up.
FM 3 obeyed the "Don't let the protagonist die" rule, while FM 4 required the field be clear of friendlies.
Custom Robo has battle modes where you and an ally can fight an enemy. If you go down, your partner will automatically give up. Even if the enemy's health is almost gone, and your partner's health is almost full. This is justified when Harry is your partner (who it most often is), as he canonically wins every match very narrowly, in-excusable when you have a competent ally.
It's even worse in the final battle against Rahu, when you have both Harry and Marcia as your allies in a 3 vs. 1 fight. If either of them are knocked out, you're still forced to fight, but if you're knocked out it's an automatic loss, even if your partners aren't. Especially bad if one of them is at near full health.
Dungeons & Dragons Online averts this one: If you have a hireling of some sort, you can have them grab you "Soulstone" (Pretty much your dead body) and lug it to a resurrection shrine.
World of Warcraft averts this in some cases where the player is asked to take part in a battle. Certain battles are large events that start when one player accepts the quest and allow other players to join in at any point. These battles will always end in a scripted event that unfold exactly the same way, even if only one player is taking part and that player wandered off to make a sandwich. The players also usually receive a buff that makes it virtually impossible for them to die during the event (though freak accidents have been known to occur).
On the other hand, if a PC dies, any pets, guardians, or the like (the difference is generally the degree of control the player has over the NPC) will also instantly vanish. Which makes it frustratingly/amusingly obvious (depending on which side of the equation you are) that the Hunter that just Feigned Death is not actually dead; his pet is still attacking...
Atlantica Online plays it straight; your main hero is denoted by a pair of rings, and if he dies, remaining companions flee the combat. You're considered dead (though any hired mercenaries that fled still have their HP/MP), and teleported to the nearest town after a almost always modest Death Penalty.
In Kirby's Return to Dream Land, players 2 - 4 can play as Kirby, Meta Knight, King Dedede, or Waddle Dee. If anyone but player 1 dies, they just disappear, and can respawn by taking from the pool of extra lives. In fact, they can do this endlessly, even if the lives run out. If player 1 (who is always Kirby) dies, though, regardless of how the other players are doing, it's back to the beginning of the level.
In Yu Gi Oh The Falsebound Kingdom, you fail if all Yugi, Kaiba, or Joey's monsters are killed. If other characters are beaten, they'll eventually reappear at your main base.
Pikmin, where if Olimar is beaten up too badly and runs out of health, the day automatically ends, quite potentially resulting in the loss of a lot of Pikmin.
Justified by the fact that the oxygen in the atmosphere is poisonous to Olimar, meaning he has to run back to his ship and make repairs to his suit if it takes too much of a beating or face certain death. And Pikmin are a race of too dumb to live plant creatures that were essentially moving sentient snacks for the native herbivores before Olimar began commanding them.
In Age of Empires II regicide games, if a king dies, the king's civilization is considered defeated.
In Pokémon Mystery Dungeon: if the protagonist, your partner, or an escort NPC is knocked out without a Reviver Seed, you're instantly tossed out of the dungeon, drop all money, and a number of your items.
Should the PC in Diablo 2 die, his hireling and any summons also spontaneously fall over dead.
And on the side of villainy, one battle features Lord Crump and a plethora of X-Nauts. Want to win? When it's your turn, ignore the X-Nauts and target Crump. Less on the side of villainy, defeating a Gold Fuzzy causes the Fuzzy Horde it summons to disperse.
Parasite Eve 2 uses the protect the key character element twice. When Aya and Kyle team up and battle in a few points in the game, the game ends if Kyle's HP hits zero. There is absolutely no way of healing him, even though you could have the ultimate healing spell and best healing items at your disposal, which seem to be marked for only Aya to use on herself. Once Aya meets Eve in the Neo Ark research facility, they are ambushed by golems. The enemies fill the room with poison gas and Aya has to convince the Eve to leave with her in order to escape. If too much gas fills the room, Eve will stop moving and cough as her HP depletes, making it harder to guide her. The game ends if Eve dies.
The Darkspawn Chronicles expansion for Dragon Age: Origins explores what would have happened if the player character had died in the beginning of the story, in the Grey Warden initiation ceremony: Alistair would have gather the team members in your place, but in the end, they would not have been able to defend Denerim from the darkspawn invasion. You play as a darkspawn in this expansion.
Neverwinter Nights: Averted in many ways. If your rogue main character fails her save against a death spell, the game over screen displays... except the battle keeps going after you're dead, so if the half-orc behind her could probably splat the Squishy Wizard that cast that death spell and win the battle in a single hit, it will. Also, for a majority of the first campaign, parts of the two expansions, and most user-created modules — you can respawn at said temple with just a small loss of EXP and/or gold, your henchmen warp back to the temple with you, and you can then jump right back to the spot where you died. Secondly, the 'game over' dialog goes away if another player casts Raise Dead on you, and in multiplayer you can click "Wait for help" to make the dialog vanish while you stare at your corpse for this reason. (In fact, it's entirely possible in single-player to have a script resurrect your character after the game over screen pops up, bringing you right back into the action] against an unprepared AI. You can even place overrides that allow this to happen in any campaign.
Baldur's Gate uses this trope. Explained by the fact that your character is the mortal child of a dead god, and death immediately releases his/her "essence" back to its godly source; resurrection spells don't work too good when the post-death cutscene shows your body crumbling to dust. This explanation isn't consistent, however; the same should apply to Imoen for the same reason, but it doesn't, and it also works less when hit by spells like Flesh to Stone or Imprisonment, which explicitly do not kill you, so if the game would just hold on a moment, you might be able to bring the character back.
The PlayStation game Journey To The West has the monk Sanzo who causes instant game over if he(or she, as you can choose gender at the start of the game) dies in battle. Annoying in three battles in the game:
First when you have to deal with a gourd that will suck up one character every other turn(and you will lose at least one character to this.)
Second is the breakaway floor fight(which can be easy if you remember to use Cavilier in the fight)
Third is the "Sanzo gets turned into a tiger and attacks you" fight where you get told that even though he can attack and kill you in the fight you can't do the same because Sanzo is Sanzo regardless of form.
Quite handily averted in Brave Soul. Since your Arbitrary Headcount Limit is Rudy, plus three other characters (usually his dragon and two other girls), when Rudy goes down, it isn't over until all your teammates are also down. Very good when one of them is the resident healer, very bad when none is or no one has that game's equivalent of a Phoenix Down.
Both Knights of the Old Republic games used a similar "just incapacitated" system for everyone, thus neatly averting the trope by letting your take control of a teammate if the main character was downed. It's played dead straight in Mass Effect and Jade Empire though.
Rather odd in Jade Empire, since the main character actually does die at one part, but the party actually does go on without them. Any other time the main character is knocked out, however, results in this trope.
Probably because in this one particular instance your death was prepared for beforehand, with the Goddess of the Dead gathering enough power to bring you back to life and guide your party to where you are. Dying at any other time screws up her plans and leaves her unable to help you.
... well, unless Shepard's allies just used Medi-Gel to revive him/her, as they themselves are revived near-constantly. This is, incidentally, the biggest difficulty leap between multiplayer and single player, as well, since the multi-player has no problem letting you get revived, making high-risk tactics more viable.
In pretty much everyShin Megami Tensei game, this trope applies. In most, it makes sense - the player is fighting by contracting demons, therefore when the player dies, their contracts end and they have no reason to continue doing whatever the protagonist wanted.
Both Persona 3, and Persona 4 play this straight at first. Both then have a lot of fun justifying it later with major plot twists as the games approach conclusion. In 3, the player is the container for the 'Appriser of Death', Nyx's herald. If he dies, Death is freed instantly, Nyx awakens, and since only the protagonist had the power to seal her again, she destroys the world. In 4, the protagonist represents 'Hope' in Izanami's test of humanity. Just like the other two 'players', Emptiness and Despair, he will be removed from the test if he's defeated... which leaves Izanami and Ameno-Sagiri free to run through the plan for Instrumentality that Emptiness has convinced them the world desires. That doesn't explain why the other characters can't just throw a revival bead like you can for them, though.
It's possible that the other characters do throw a revival bead at you, but if they did, the game would be Unwinnable by Design with death already being released/"Hope" being removed from the test. And no one wants to go through that,
Devil Survivor does it a little different. Characters and enemies are in squads, and if the leader dies, the rest of the squad disappears. Makes sense for Human summoners, not so much for Demon squad leaders. Unless the mission specifically states a certain character must live, anyone is allowed to be defeated. Most of the time, you simply need at least one member of the Main Character's party to survive to the end of the battle. This member does not have to be the Main Character.
In the boss battle with Beldr, the defeat condition is specifically the death of the Main Character. This is because only the Main Character has the Devil's Fuge (and thus, the only character that can damage Beldr), so if he dies, Beldr will be left unchecked and free to tear up Tokyo. Later on, however, when you rematch with Beldr, this condition is not in place; you can be dead and the battle will keep going, but unless another live character or demon has a revival spell and uses it on you, the battle becomes Unwinnable by Design.
In Shin Megami Tensei I and Shin Megami Tensei II the main character can be killed in a battle as long as at least one human character remains alive. However, when the main character is dead all COMP functions are inaccessible, so no summoning other demons or looking at the map until you revive him.
Shin Megami Tensei Strange Journey works this way as well, with a twist: the Stone status effect counts as death for the main character. While there are items that act as insurance against instant death attacks, they don't work against Stone.
Soul Nomad & the World Eaters. Although the fact that the main character is borrowing the powers of the master of death might explain why all your companions can be summoned to die time and time again.
Also, the rest of your party is simply being summoned to the field through the powers of Gig. And if Gig's host dies, so does he.
In Valkyrie Profile, the other (dead) characters are kept in existence by "Divine Materialization Energy" supplied by Lenneth. Leave her down for three turns and the party explicitly is said to cease to exist.
Kakurenbo Battle Monster Tactics, while (at least generally) not a case where losing means being dead, has the objective in most/all battles for both sides being to defeat the enemy leader. Oh, by the way, the player actually loses if the enemy leader is finished off by an enemy's friendly fire.
Used in Kingdom Hearts; Donald, Goofy, or your guest party member can get KO'ed and revived freely (and often do), but Sora hitting HP 0 means his heart's gone and he's dead. Averted slightly in the sequel, where in some boss battles, even if Sora hits HP 0, Mickey freakin Mouse comes out of nowhere to save him.
Also, in Coded, there is the Final Fantasy-esque Olympus Coliseum, where you still get a Game Over if Sora is killed (unless he's under the effect of Auto-Life), whereas Hercules and Cloud can be revived with a simple Cure spell. Somewhat Justified by the fact that they can't heal you at all.
The tanks in Dragon Quest Heroes Rocket Slime each include a small shrine where any crewmember who dies in battle will reappear moments later... Except the main character Rocket.
In Secret Of Evermore, you can revive your dog if he falls, but he can't revive you. You have to be under the time-limited effect of a revive-me-if-I-die item if you don't want your death to be instant Game Over. Justified by the fact that he's, you know, a dog.
In Arcanum: Of Steamworks & Magick Obscura, if your main character died the game would remain active for a short time while your followers attempted to resurrect you. Of course they weren't very smart about how they went about it and would frequently try to use methods that wouldn't work (i.e. use resurrection spell on a technological character or technological resurrection on a mage). One side quest actually required that you do this.
Saga Frontier does this as well. Every character has two life meters, in the form of Hit Points and Life Points. Losing all of a character's Hit Points merely renders them unable to fight, and they will get back up and continue battle once they're healed. However, Life Points (which are lost if a character is attacked while at 0 HP, and also from a few attacks that target LP directly) are different, since if a character loses all of them, they're dead as a doornail, and will remain as such until you get them to an inn (or use one of the incredibly rare Sanctuary Stones found throughout the game). If the main character of a scenario loses all their LP, however, it's an instant game over, even if everyone else on the team is perfectly healthy.
Appears in one short quest in Final Fantasy VI, though somewhat justified as Bannon, the man you must protect, is the leader of the rebel movement. Also made easier than some other cases as he has a unique ability that heals the entire party without using magic points.
Final Fantasy IX has this trope in the beginning of disc 1. Vivi, and then Garnet are captured by a plant monster and the monster gradually sucks up their HP. Vivi can cast Fire on the monster on his own while Garnet is helpless. Should either character have their HP be reduced to 0, Game Over.
It's back in Final Fantasy XIII, in which it's game over if your party leader (the only character you control in battle) goes down. Anyone else can be revived with a Phoenix Down or Raised via spell, but your leader cannot — whoever your leader may be at the time.
Especially annoying when Hope or Vanille, the two most fragile characters, are party leader.
In Valkyria Chronicles, if Welkin falls in a battle, it's Game Over—even though any other character can go down from a tank shell to the face and be revived by the medic if another character touches them in time. Thankfully, Welkin drives a tank so he doesn't usually go down easily. This might actually justify the trope as the tank explodes.
Note that you do gain another tank unit later in the game who can be blown up and return next mission, but even this can be explained away as he drives a standard tank, while Welkin's Edelweiss was a unique model built by his late father, and would therefore be almost impossible to replace.
Plus, any of the other main characters will simply retreat from that particular battle if they go down and aren't revived in time (or if an enemy gets to them first). Meaning that you can actually be LESS careful with the main characters than with the story-unimportant recruits, which have the opportunity to be perma-snuffed.
Chrono Trigger averts this trope. You can follow an optional side quest to recover the main character but you certainly can win the game without him.
Wizardry: Tale of the Forsaken Land does this, but only with perma death. Normal death you can simply revive your main character after, same as anyone else.
If Materia dies in the first Aretha game on the original Game Boy, you get a game over. Especially annoying once Doll gets resurrection magic, as it means that the magic is only usable if Civil dies.
Phantasy Star Universe: In the story mode, the defeat of hero Ethan Waber ends the game, unless your party members are able to revive him.
In the RPG Okage: Shadow King, if the main protagonist Ari is KO'd in battle, it results in an automatic Game Over even if the other party members are alive and revival items/abilities are available.
Understandable, considering Evil King Stan is using Ari as a vessel. If Ari goes down, Stan can't do a damn thing and his teammates will probably forget about him.
Tales Of Symphonia has one part where the main characters volunteer to rescue a woman from dying the death of a Ancient Roman in the Colosseum. To accomplish this, one party member needs to win one Colosseum battle so they can subsequently sneak into the holding cells. If her or she is defeated in that battle, the game is over. This doesn't necessarily mean the character dies (losing any other arena battle never kills the character), but presumably you can't sneak into the prison if you lose and the prisoner will be excecuted.
Resonance of Fate applies this to all three of your characters; any of them die, it's game over. Justified though in that there are no revival items and the game does give you the chance to redo the battle for a small fee.
Done in Mystic Ark, though it's somewhat justified as that the main character is the only one who can directly control the power of the Arks, which is the only think that makes your allies able to fight. Since dying just takes you back to the last place you saved, one can assume that either your team or the power of the Crystal warps you back.
In Lufia The Legend Returns, you can have up to 9 characters in battle at a time. They will be displayed on the screen in a 3x3 grid. If the first character in each vertical row dies, the game ends, regardless of what condition the rest of the party is in, and the fact that reviving characters in this game is incredibly easy. Even more interestingly, you can get this game over even if the main character is still alive!
Arcana has this rule, with a twist: If any character other than an elemental spirit dies, it's automatic game over. Granted, there's no item to bring anyone back to life and all the characters will be used at the end to help you reach the Big Bad, so they do need to be kept alive for that reason.
In The Magic Candle, your five recruited party members are allowed to stay dead (you can always go recruit more), but if the main character dies, that's the ball game. There isn't even a Bad End screen for this — you just get booted to DOS with the message "[Hero's name] died and wasn't resurrected."
Fallout games instantly end when the player character dies, no matter how many NPC followers are still standing, rather like Arcanum without resurrection options.
Which is especially jarring in Fallout Tactics, where the PC is the sergeant of a squad, not any form of Chosen One.
As a Mons series where you fight alongside the monsters, Geneforge justifies this in much the same manner as Shin Megami Tensei. This does get a bit iffy in 3, though—it's the first game to give you human allies, and unlike in 4, they're immune to the Final Death that plagues all other allies in the series. Your stalwart swordsman or knife-toting mage can fall in battle a hundred times without a game over, even though you lose the game if you fall even once.
In Ultima VI, if the Avatar dies, while there's no Game Over, Lord British will immediately summon you and your entire party home, and bring the Avatar back from death.
Used partly in Ultima IV and Ultima V, in that while the party can still go on without the Avatar, the Avatar must be alive and active for certain things to happen; in Ultima IV, speaking with Lord British will revive a dead Avatar candidate.
In Infinite Space, you can command up to five ships in your fleet. If the flagship gets destroyed, the game is over, no matter how many ships are left. This is probably because the player character was standing on the bridge and took a laser cannon shot to the head.
In Gatling Gears, this trope applies to both players in a 2-player game. If one player runs out of lives, it's Game Over no matter how many lives the other player has.
The original Rogue Squadron on the N64. If any of your fellow Rogues gets shot down, they do an emergency landing, and you can see their downed X-Wing safely on the ground. If you take too much damage, you explode.
Multiplayer in X-Wing Alliance let you take command of other vessels in your wing if you died. Singleplayer, not so much.
In the Lost In Blue series of survival games, the game is automatically over if any of your characters die, even if the others are healthy and well with a good supply of food and water. Even if they're standing only seconds away from escape from the island. Regardless.
The Oregon Trail: The first game avoided this, in that your main character is invincible until your party members all died off. In later games, this is mostly retained, but before that, the main character can still suffer other injuries (starvation, thirst, accidental gunshots, animal mauling), and their death immediately ends the game.
Subverted in Wing Commander Armada, where your fighter being shot down would dump you into the cockpit of one of the surviving fighters (assuming you sent a group of fighters), if you didn't select the auto-combat option. Played straight in pretty much every other game in the series.
Averted in Strange Adventures In Infinite Space and its Weird Worlds remake/sequel, where your starting ship can be lost in battle, yet you can continue with one of the other ships you have picked up along the way. However, since most of your best equipment is likely to be on your primary ship, it's almost not worth it to continue the campaign (which takes all of 20 minutes to beat anyway), as you're not going to get a very high score.
Resident Evil 5 ends the game if either Chris or Sheva dies. Thankfully, the computer is intelligent enough to heal/revive you most of the time when you hit Dying.
Third Person Shooter
In Fur Fighters you have six characters, they have the ability to transport all over the worlds you visit and okay so only one person can be deployed at once fair enough but if one dies then the other 5 can't just take their place?
Alien Swarm does this if a level requires a Tech and the said Tech gets killed.
Gotcha Force is guilty of this. In particularly irritating levels it's better to have a large force of weak Borgs than a small force of strong ones; if your force goes down before your ally's, you lose the battle, regardless of how strong your ally's force is.
The Godfather 2 is a double subversion. If you die and there are Medic-trained allies nearby, they can revive you... but if there aren't, you will die even if there are other allies around.
Turn Based Strategy
In Final Fantasy Tactics, a character who is KO'd and is left that way for 3 turns will die off forever. This also applies to the main character, Ramza, where the game will end if he ever gets killed off, no matter how many other people in his party are left standing. Unlike some other examples, normal revival methods CAN be used to revive Ramza before the countdown reaches 0. Characters involved in an Escort Mission, however, have no such protection, as the game will end as soon as they're KO'd even if you could revive them on the next turn.
Final Fantasy Tactics Advance also applies this rule to the main character, Marche, where the game will end if he dies in a Jagd. However, the game also ends if Marche gets tossed in jail during battle. Both games also feature battles where a key character must survive and ends the game if they have fallen.
In the Total War games, you play as the current head of the ruling dynasty of your faction or clan. Should the ruler die without heirs, the game ends. In some of the games, by the time you get about midway through the Grand Campaign, your royal family will have so many people in it - through childbirth, marriage, or straight adoption - that you could lose half of them and not be bothered at all.
Played straight in Silent Storm and its sequels. The only character who is not allowed to die is the Player Character (if the main character is at critical health and bleeding, he'll helpfully report, "I'm bleeding here. Don't wait too long, or it could be over... for all of us.") If another squad member dies, another one can be recruited back at the base. There are a limited number of recruits, though, and they all have different skills. On easier levels of difficulty, characters are merely knocked out and are revived after the mission. Once again, this does not apply to the Player Character.
In most scenarios in the open-source strategy game Battle for Wesnoth, the death of your 'leader' (commander unit) will lose you the scenario. Somewhat justified in that the leader is the only one who can recruit new units. Also justified in that there's no resurrection option for any character: Death is very, very final. Played straight with several minor characters in many scenarios.
Most missions in both Vandal Hearts games have automatic failure conditions if the lead character is defeated. Other characters, however, can be killed with fountains of blood pouring out and are then fine the moment battle is over.
Vandal Hearts II ups the ludicrousness when all friendlies have a skull mark indicating death count, with one big mark indicating tens. Your allies can have 30+ deaths while the main character can't ever have any.
Yggdra Union. The game ends when either Yggdra or Milanor dies. There are also some characters that you can't lose for certain battlefields: Rosary or Roswell can't die on Battlefield 11, Cruz can't die on the battlefield you recruit him on, Elena can't die on Batllefields 25, 27, 36, and 37, Gordon can't die until halfway through Battlefield 32, and Kylier can't die on any battlefield before 42. There are also some battlefields where you just can't let anyone die.
Every Ogre Battle saga game has this, including the Tactics Ogre games. While your main character often becomes one of your strongest party members in terms of stats + abilities, he/she's a huge liability since it's Game Over after he/she goes down. This is especially troublesome as many of the later levels it is common to perform many resurrections.
Every single character in Odium. Anyone dies, you lose.
Lose a character in Fire Emblem and they're gone for good. If one of the viewpoint characters is taken down, the game ends. The same applies to escortees during an Escort Mission, but those are surprisingly easy to get through if you're careful.
In the Shining Force series, you lose the battle if the main character is defeated. However, there is no "Game Over" scenario, instead returning the party to the last save point, usually a church, where you can revive other fallen party members. The only downside is that you lose half of your gold when defeated.
Not only that, but most of the time there's an opposing investigator pressing their version of events; if Edgeworth is unable to disprove their theories, then that means the wrong person will be arrested. In the case of the Final Boss, he's influential enough to justifiably leave the country if Edgeworth and co. aren't able to crack his testimony. On top of that, there's one case where he's locked in a room and has to escape, and another where he's the accused to begin with, in which case things really will go south if he can't figure it out.
The main issue being that you never enter court in this game, Edgeworth only talks out in the open to his suspects. While winning leads to their arrest and subsequent trial, losing means that the upcoming trial will ALWAYS fail to find the true culprit (you know, basically the opposite of every single Phoenix Wright case where the wrong person is arrested and you have to uncover the truth anyway). It seems you can count the actually capable lawyers in this world on one hand.
Non-video game examples:
Alien mercenaries in The Fifth Element will not fight without their leader. This makes the best tactic when they take hostages and demand to negotiate identifying the leader and blowing his head off.
Korben Dallas: Anyone else wanna negotiate?
In Chess, the lynchpin to both sides is the King. Whenever either King is threatened with capture (Check), the threatened side has no choice but to spend their next move getting the King out of danger. Oddly, the King is never captured - the game ends when the King has no way to escape impending capture (Checkmate) with the King (and his side) surrendering.
In Sid Meiers Civilization The Board Game, the lychpin to each side is his capital city. Capturing that will immediately end the game in favour of the player who managed to do so.
In Warmachine and Hordes each army is led by a powerful spell caster. Either a warcaster or warlock depending on which game. If your warcaster/warlock is killed, you loose the game regardless of how the rest of the battle is going. This is justified if your army is heavy on warjacks/warbeasts, as they require the caster's direct control.