A blanket note for several of the examples below: While it's hard to confirm because the ESRB criteria for rating games isn't entirely transparent, a number of people have alleged that allowing the player to deliberately murder children in a game is a fast track to an Adults Only rating; this would be financial suicide for any title with a multi-million budget as all major consoles prohibit AO titles on their system and few retail stores (and no major ones) will carry them. (This may have carried less weight in the 90s, especially for PC games which got lax treatment to begin with.)
In the second Baldur's Gate game, the PC frees the inmates of an asylum for those driven mad by magical power to help take on Big Bad Jon Irenicus. One of these inmates is a young girl with the ability to shapeshift; she does not actually take part in the battle, in which all the other inmates die.
Children seem to be actually "immortal" in this game, at least those playing in the streets of Athkatla.
Castlevania 64 has the hero fighting horrible menaces to save a human kid named Malus. Then he sends him off into the monster-filled worlds. The rerelease had a different hero give a different kid a plot coupon that would protect him from said monsters.
Subverted in Malus' case since he's freaking Dracula reborn. In the true ending you get to confront and kill him.
No children or infants appear in the Crusader series of games, because with the care most players usually take to avoid killing civilians there would be frozen, burning, or gooey babies everywhere. And you can't get baby out of carpet.
In Dragon Quest V, during the segment where your characters are children, they don't die when they hit 0 HP, but are just knocked out until the end of the battle. Actual — if not-permanent — death isn't an issue until your lead character is an adult.
Subverted with the PC's own children who CAN get killed in battle
Fable: The only children to appear are in a town which the player cannot enter without leaving his weapons at the gate.
You are never unarmed in Fable II, but no matter what you use, you can't kill the kids. Oddly subverted in the intro sequence, in which Lord Lucien shoots dead your sister Rose, who is barely older than you are, and then shoots you with enough force to send you through a window and down a fall you only survive because of your magical heritage. Near the game's ending, Lucien will kill your spouse and children, offscreen.
Unlike its predecessors (see below) where killing a child would give you the very negative child killer rep, Fallout 3 makes children completely unkillable. They'll survive mini-nukes undamaged. This restricts an Evil player's options in Little Lamplight, a town populated entirely by kids. While children are invulnerable to harm, a "creative" player will discover that you can enslave some, sell drugs and guns to them, bully them, taunt one to run away from his neglectful mother and the evil solution to the "The Power of Atom" quest (detonating the atomic bomb) will kill the two children living in Megaton.
It's actually still played straight during "The Power of Atom." If you activate the bomb but do not detonate it, leave town, and come back before you finish the quest, you'll find that the two children in Megaton have mysteriously vanished.
In addition, the company that made the game explicitly prevents discussion of game mods that allow child killing on the official forums, and has had videos of child killing mods removed from youtube by claiming copyright infringement.
There are also points in the story where the player character is a child during the game. You however are not affected by miraculous immortality other wasteland children have and can kill a child via killing yourself.
They've continued the policy in Skyrim, where again children are immune to damage.
Not only that, but the child seen in Helgen, the town destroyed at the beginning of the game, was specifically shown to escape the dragon and can be found later on as one of the few survivors. The Dark Brotherhood questline has one that just looks like a child, having been turned into a vampire centuries earlier, but when the sanctuary is raided and destroyed during the questline, she is one of the survivors - and is not there at all if the player chooses to wipe it out himself instead of joining.
There are, however, mods that avert this trope, allowing kids to be killed like any other non-essential NPC. The fact that killable children was one of the first mods made says alot. These mods can be seen as mods only sick people would play, or mods that enhance a player's sense of immersion, bringing the game closer to real-life.
Fallout: New Vegas picks up this policy from its predecessor. The game makes a point of this feature by including a quest where one can find a range finder in order to use a prewar super weapon, the ARCHIMEDES II. However the player character needs to obtain said rangefinder from a child named Max who believes that it a toy. Max can not be killed in order to get the rangefinder off of his body, you must pay him a thousand caps (20 with a high barter skill), or pick pocket him. However Max constantly runs so it is impossible to pick pocket him unless he is asleep.
This is applied strangely in F.E.A.R. Alma is already an Implacable Man, but the moment you have to actually face off against her, she goes from her Creepy ChildStringy-Haired Ghost Girl form to a teenage one. This makes absolutely no sense plot-wise, and seems to be solely so you won't have to face down and eventually shoot a little girl — even one that's already dead.
It does make sense in the way that Alma is actually grown-up, since she already gave birth to the player character. Thus, you see her "real form" instead of the mind-projection of a little girl.
Canonically, she was an adult when she died — but, IIRC, only fifteen when she gave birth — but she was unconscious nearly the entire time, and would have no frame of reference for herself looking like this. It doesn't make a lot of sense that she'd psychically project herself as what is, to her, virtually a complete stranger, rather than the image she probably has of herself.
There's also the small matter of Alma raping the main character at the end of the second game. Doing that while she still looks like a little girl would probably cause even worse publicity than being able to shoot her.
In Final Fantasy Fables: Chocobo's Dungeon, the journey into people's memories starts by chasing a mysterious flying infant, worried that he'll be hurt. He somehow manages to escape the monsters unscathed, though Chocobo has a hard time finding his way through.
Grand Theft Auto: In a game where you can beat people to death, blow up cars, and just be an all around psychopath, there are no kids.
Averted in Limbo, seeing as nearly every reaction to you screwing up a puzzle in that game causes your protagonist (a small boy) to meet a grisly and painful death.
The reason why there aren't any children in Half-Life 2 - so they can't be killed. The game designers turned it at their advantage though: the childless city was explained in-game by a "suppression field" which prevents certain protein chains necessary for embryonic development from forming, according to Doctor Kleiner. There's a great atmospheric moment at the start of the game, when you pass by a playground and, if you look at the deserted swing and the broken doll on the ground, you can hear a distant, fading kid's laughter.
Amusingly lampshaded once the suppression field goes down - Kleiner suggests via broadcast that, while the Citadel's reactor is going critical, "now would be an excellent time for procreation" for those who are out of the city.
Depending on which games in The Legend of Zelda series and how good the player is, this can either be played straight or subverted with a child Link.
In The Sims 2 and The Sims 3, babies and toddlers cannot be killed in any way. If they are caught in a fire they will miraculously escape, and if their needs drop too low, a social worker will take them away. The same is true for children, except they actually can burn to death, drown, or get crushed by a satellite or meteor. They just can't get electrocuted, scared to death, or starved to death (the social worker will come first). Pregnant women also cannot die. However, ghosts in 3 can reproduce (with other ghosts or with living Sims), and the babies are sometimes ghosts who will then age like normal Sims.
This is in full swing in the Siren series... which actually works against the player, as they enforce it by having children panic and curl into a ball before they're actually even hit, yielding a game over. If you're playing one, you're currently playing a stage where not using stealth, rather than just being dangerous and wasteful, is completely impossible. If you have one with you, you have to take great care to protect it — and a stray hit during combat that connects with them causes them to panic as well.
Both an example and exception in Siren: Blood Curse. On escort missions, you can hurt and kill the person you have to protect. Except 10-year-old Bella. Your weapon has no effect on her. Likewise, enemies can hurt and kill escorts... but when Bella "dies" it's by covering her head and cowering in fear. And when you play as Bella, instead of taking damage from enemy attacks and eventually dying, you cower in fear and scream "NO!" if an enemy gets too close to you, causing you to lose. Technically a way of avoiding showing Bella's obvious death. Yet, the game also creates an exception later when Bella is shown later on having turned into a shibito, the zombie-like creatures in the village. The condition for becoming a shibito is to die, so obviously something happened to Bella. An earlier cutscene shows a large log rolling towards her and a quick cut to black, indicating that's what might have killed her.
Tails from Sonic the Hedgehog cannot die if you play as both Sonic and Tails in Sonic 2 and 3.
World of Warcraft follows this to a T. You can slaughter whole towns, but not the children in them. Apparently it's better to let the children get along without their parents that you slaughtered than to also kill them. Then again, given respawn, that's not an issue...so it raises the question of why one can't kill a level 5 child since they'd just come back anyway.
The reason is, Blizzard doesn't want either side to seem Always Chaotic Evil to the other, and child murder is a good way of crossing the Moral Event Horizon. This is also lampshaded with an in-game holiday dedicated to helping the orphans in every city.
Averted somewhat lore-wise, given the presence of NPCs such as Pamela Redpath.
Even then if an undead child has to be depicted, they have to be depicted as that of a ghost. So yeah, no zombie kids for Children's Week.
It's only to be expected that Zoo Tycoon would honor this trope, being a family game. It's worth mentioning because of how blatantly the Infant Immortality rule is applied: if predators escape or a guest ends up in their enclosures, they'll leap on and attack adult guests, while completely ignoring children. Hence, a runaway lion or tyrannosaur will charge right past a dozen kids to pounce on a grown-up.
The Sonic Blast Man arcade game (as well as the SNES version) featured a stage where the player must punch out a truck that is about to cross path with a runaway carriage with a baby boy inside it. If the player fails the stage, it will show that the carriage managed to get safely out of the truck's way, only for Sonic Blast Man to get run over in its place.
However averted in a battle of Shining Force III where three of the five refugees you're tasked with saving are children, they have the lowest hit points in the group so the enemies will target the children over the adults. And yes, you are treated to a 3D cinematic of enemy knights slaughtering helpless civilian children.
In Virtue's Last Reward, Quark is the only person you will never explicitly see dead. Everyone else is fair game.
Though it is highly unlikely he survives any of the endings where the whole facility goes up in an explosion.
In Final Fantasy XII, you will occasionally be joined by a fourth party member. The only guest party member who doesn't eventually die is Larsa, who is twelve.
In the Japanese version of Scribblenauts, child NPCs have infinite hit points.
In Nira Oni, a group of teenagers gets trapped in an Abandoned Hospital. Although they're all in danger, most of the cast show particular concern about Cassey's younger sister Ryan, and this directly factors into the ending. Hiroshi can decide to ensure she escapes at any cost, meaning she survives even the worst ending... but at the cost of everyone else.
In Terraria, the Angler is the only child in the game. He can be hurt by monsters or traps like the other townsfolk, but instead of dying bloodily like the others, he vanishes in a puff of smoke with the message "[name] has left" when his health runs out. Since this is how some phantasmal enemies like the Wraith "die," the most popular explanation is that he's a ghost, so whether this is an aversion or not is unclear.
In the classic Commodore 64 game Mad Nurse, the entire premise is trying to prevent wandering babies from blundering into poison, electrical sockets, high-flush-power toilets and even elevator shafts. If you do nothing, almost every baby in the ward is guaranteed a gruesome death.
In Fallout and Fallout 2 it is possible for the player to kill very young children, though doing so earns you the "Childkiller" title and greatly decreases your reputation. The European release of the game was Bowdlerised specifically to prevent this (to the extent that certain quests cannot be completed, and the player can have their items stolen without realizing it). This is commented on in Fallout 2.
The first two Fallouts avert this trope with such fierce glee that probably some of the most vivid and horrifying descriptions of critical hit damage in the games come from shooting a child in the eye, or blowing off a leg, or firing a minigun at a groin, and so on.
For reference one player semi-famously played through the entire game in a completely non-violent manner as even the final boss fight can be resolved with words. He did, however, kill every single child in the game.
Horribly, horribly averted in Dwarf Fortress - children can die in any number of ways, and military mothers will carry their infants into combat, where they are very likely to get impaled and upset said parent. On the other hand, if you can offset the mood loss, children make excellent body armor.
Moreover, sometimes the mother uses the child as a blunt weapon
Shadow Hearts: Covenant subverts this, albeit with a young girl, not a true baby. Early in the game, a young girl is taken hostage by one of the villains apparent. In keeping with the trope, she apparently escapes in the scuffle... but shortly thereafter, we find out she was killed off-screen when she appears as Yuri's Spirit Advisor.
Averted in the Star Wars: The Phantom Menace game. You can kill children who conveniently run in front of you, even after already killing a few of them.
In Dead Rising, the hero offers to help a hysterical mother find her missing baby only to be told that she saw it eaten by zombies.
The opening cinematic has a woman and her child trying to escape the zombie horde in a car, but they crash. It fades out with the zombies surrounding the car, with the child trapped inside.
Tales of the Abyss subverts this during the destruction of Akzeriuth. After the city's complete decimation, the first thing of the aftermath that the heroes see is a small child crying out in pain and screaming to his parents, dying as he sinks into the hot mud of the Qliphoth. Kinda chilling and really hits home at how horrible the devastation is.
Zig-zagged with the death of Fon Master Ion. He's almost old enough not to count... except that he's a replica, so while being physically fourteen might disqualify him, he's mentally 2 years old.
Averted later when Fiona and her troops attempt to rescue several civilians, two of whom are children. If the knight carrying the child dies, the kid will be exposed to enemy units who are almost guaranteed to make a beeline for it.
Seisen no Keifu also features child civilians, and yes, enemies will kill them given the chance. Given that saving one grants an automatic Level Up, it's in your best interests to save them.
Averted in Max Payne, in which Max's newborn daughter is murdered at the start of the game, though the body is mostly concealed in the PC version, and completely concealed in the PS2 port. Still, there's no mistaking the rag-covered lump in the bloody cradle for anything else.
Avoided numerous times in Alter Ego. At several points during childhood and infancy, it's possible to inadvertently kill yourself or severely injure yourself by food poisoning, a falling iron, or numerous other means.
At one point, a bad choice can result in your character (while a child) being kidnapped, molested, and murdered by a pedophile.
In Clive Barker's Jericho, some of the enemies that the Jericho squad have to face are simply known as the Children: hideously mutilated, demonic child spectres, who are the souls of a child army that was massacred during the time of the Crusades.
Subtly averted in Final Fantasy II. In the beginning of the game, in the various towns you can travel to, here are many child NPCs you can talk to! After the Imperial Dreadnaught goes on its first run...there are significantly fewer child sprites left, and some shell-shocked adults NPCs grieving their sons and daughters. And then the Cyclone starts its world tour...
In Final Fantasy VI, Kefka wipes out the kingdom of Doma via poison. One of the main character's family is in Doma, and as he rushes in to warn about the poison, he discovers his wife dead, and as he opens the door, the corpse of his son falls out of the bed. And that was the moment where Kefka lost his charm.
In Final Fantasy X, there is a cutscene in Kilika where children are playing with a blitzball near a mother with her baby. Then Sin comes and attacks the villiage. The last thing that you see is the blitzball in the wreckage. Later, when Yuna does the Sending, you can see a very small casket among the dozens in the water, and you see the mother breaking down back on shore.
Deus Ex has a number of (male only) kids around, all of whom are viable targets. One of them is, in fact, a Jerkass most players relish killing. The sequel, Invisible War, is no different: you can go on a rampage in a girls' elementary school.
Scott: You can gib a child with one stroke of the nanosword! Chris: Thatís because children have fewer hit points. They are inferior and weak.
Advance Wars: Days of Ruin features a virus (Endoflorus Terriblis) which kills only children though it mutates into killing anyone later. To drive the point home, photos are shown of a child with flowers sprouting out of his body.
Lin: He had roots and leaves growing under his skin... In his ears... In his eyes... Little roots creeping behind the eyes... ...What if you could hear them...?
In Ultima VII: The Black Gate you can find a small bundled-up baby held captive by harpies outside the first town. As the baby is considered an object, it's impossible to harm, and you don't have to feed it or change diapers, can keep it in the bottom of your pack or drop it wherever you stash your spare loot, and it doesn't make a sound. Your party member Iolo will helpfully mention that his mother is lady Tory and you should bring him to her, but doesn't mention WHERE she lives - you have to actually get a transport to get there, it's out of the way of the plot and you'll probably stumble across her by mistake. In other words, you'll be hanging onto that baby for a long time.
When you find the mother she is extremely relieved, but rather than actually taking her child herself she asks you to put the kid in his crib, in the next room. She doesn't get any further dialogue on the topic, and the game actually doesn't have a function for putting the kid IN the crib (a mod corrects this), although you can balance the tyke on the edge with no problem. Or you can put the kid on the bed, never go back, and just pretend that the mother eventually stopped walking around whining about her lost kid and dealt with it.
In Serpent Isle, you're attacked by a woman who carries a DEAD child. If you click on it, the avatar or a companion will lament the tragedy. (Curiously, the dead baby is just as effective as a live one at soiling diapers, which are super-effective fear inducers, so you can get some use out of it if you don't mind being a psycho.)
A possible implication is that the woman was actually pregnant, and the child you find is a fetus.
In all Ultimas after the first three games, you can initiate combat with and kill the children you meet. In Ultima VIII, there's no Karma Meter, so there's not even any consequences for killing them.
In Ultima IX, the aversion and the karma penalty are lampshaded and delivered as a Player Punch, twice. One is a hostile spellcaster and the other is doomed whether you show the mercy to kill her or not.
The beginning of Zone of the Enders has several of the kids Leo knows tied to a light pole. As BAHRAM begins their invasion of the Jupiter space station, one of the station's mechs is hit and topples right on the kids. They even have a close up of a pool of blood seeping out from under the wreckage.
Completely averted within the first minutes of Police Quest: Open Season. In the exposition crime scene at the start of the game, open the dumpster at the back to find the corpse of an 8-year-old riddled with bullets.
Namely by being hung. In front of the player; even swaying slightly in the breeze
Obscure arcade Super Smash Bros. inspiration The Outfoxies averts this with creepy siblings Danny and Demi, playable characters who die just as violently as the rest of the cast. Some argue this is part of the reason the game wasn't found in more locales.
The trailer for Dead Island shows us a little girl getting bitten by a zombie, dying, and then turning into a zombie herself before biting her dad, who throws her out a window to kill her again.
Very very VERY averted in the Flash game: Gretel And Hansel, most of the achievements are based on finding all the different ways to die in the game. And they are heartrendingly painfull to watch.
Jagged Alliance 2 allows you to kill children just like anyone else. It comes with a massive penalty to Loyalty, like killing any other innocent civilian (or being wrongly blamed for killing one, which also can happen). The worst is when children run between you and your enemies during a firefight - they're veritable bullet magnets.
The plot of Silent Hill: Homecoming involves the founders of Shepard's Glen sacrificing one of their own offspring (though age range isn't specified), and the one child your character sees several times throughout the game itself turns out to have been Dead All Along.
Silent Hill: Downpour makes it its mission to inform you that horrible, horrible things both can and will happen to children, and how devastating it is for those left behind. In fact, with one possible exeption, every kid either shown or referred to in-game ends up dead before the end, with the molestation and murder of protagonist Murphy Pendleton's son Charlie and the actions this lead him to commit serving as the games central theme.
All of the Silent Hill games seem to have a little bit of this; a lot of them refer to Alessa Gillespie being burned alive by the Order, and in Silent Hill 3 you can occasionally hear babies cry in the background, though it's unclear whether this is real. It was originally planned for the player to hear crying babies when standing in certain locations during Silent Hill 2, but the sounds were removed because it was "too much".
Although you can't kill any children in-game, the story for Diablo states that the titular Big Bad possessed a young prince's body. When Diablo is finally defeated in the end of the first game, his body turns back into that of the dead prince. Made even more tragic by Diablo III, which reveals that the Warrior who canonically defeated Diablo was the prince's older brother Aidan. The guilt Aidan felt from killing his little brother made it easier for Diablo to possess him.
Subverted several times in the Zombie game They Hunger, sadly. In the hospital, a baby is heard crying, until it abruptly stops. The player cannot get to the nursery immediately, and when he does... There is a ribb left in the bed for newborn. And later in the mountains, the player has to kill resurrected tiny, tiny skeletons that have the hunger...
In God of War, a major plot point consists of Kratos' guilt at having murdered his wife and young daughter in a blind frenzy.
Averted in Story Mode of Mortal Kombat 9. A flashback reveals that Scorpion's wife and infant son were killed by Sub-Zero (AKA Quan Chi disguised as Sub-Zero)
Averted in Nazi Zombies mode of Call of Duty. Richtofen Kills Samantha by locking her and her father in a room with a hellhound.
Call of Duty: Modern Warfare 3: Davis Family Vacation, Day 3. A young American girl on vacation in London with her family ends up being killed by a truck bomb explosion. Which may have been a small bit of mercy, as this meant she did not suffer the effects of the nerve toxin released by the bomb that ended up killing many others.
Early in Call of Cthulhu: Dark Corners of the Earth, the player accidentally releases a monster that kills Tom Waits' daughter. It looks at first like the death will only be off-screen and you'll never get to see the body beyond the screaming and tearing sounds, but then you wake up and hear her father crying as you go downstairs....
Averted in Clock Tower, where the first game features the 14-15 year old Jennifer and her friends of the same age locked in Barrows Mansion. Depending on how you play the game, all four of them can all die. But no matter what, at least one (be it a friend or Jennifer, the player character) has to die.
Averted in Liberal Crime Squad, where the Conservatives will happily force children to work and execute them for any crimes - and the player has the option to free said children to participate in armed terrorism. It is possible to build an army out of liberated child workers. The only thing children are exempt from is sex - children under a certain age can't prostitute or seduce NPCs.
Surprisingly averted in Sonic Adventure. Tikal, who is 14, is trapped in the Master Emerald and dies from unknown causes.
Likewise averted with Maria Robotnik, who was shot down by G.U.N. when she was only twelve years old.
In the first episode of The Walking Dead, Duck survives whether you try to save him or not, but...
In Episode 4, the group comes across a boy who starved to death and became undead, and yes, it will be someone's job to put him down. In the same Episode they learn of Crawford, a walled-off fortress of survivors that weeded out the elderly, disabled, sick, wounded...and children under the age of fourteen.
Absolutely Averted by Clementine (now the protagonist) in Season 2. The world she lives in doesn't care that she's only eleven years old, and failing a crucial QTE means a gruesome demise, just like Lee in Season 1.
In Minecraft, villager children can be killed, and can even be turned into zombies.
Indie horror game Calm Time is all about people who get murdered during a Nasty Party in a countryside house. There is a little boy among the characters, and he can be killed just like everyone else. In fact, he is easier to kill than the other guests.
Child of Light: The duke's young daughter Aurora dies from poisoning in the very intro of the game. Thankfully, her soul is transported to Lemuria.
The plot of Watch_Dogs is driven by the death of the protagonist's 6-year-old niece.
In Metro 2033, you come across the shadow of a young child. You hear him cry out for his mother, and see a shadow of a mutant leap at him. Where his shadow disappears you can find a small skull. The Metro - and the desolate surface - are littered with skeletons of parents clutching their children when the nukes fell. One mission has a toddler ride on your shoulders as you try to find their mother - in a tunnel full of booby traps and mutants.
The Little Sisters of BioShock have turned Infant Immortality into an actual superpower. Having their bodies infused with ADAM makes them indestructible to anything and everything in your arsenal... unless you "harvest" them, which removes the symbiont that stores their ADAM and kills them in the process.
The "desperate, grieving mother" splicer has a line which goes "Shh, oh no... Of course you're not dying my little one. You're just a baby... Babies don't die."
Rescued Little Sisters can also die after you save them if a stray turret rocket or fireball from a Splicer hits them, but this is unintentional.
While earlier Fallout games avert this trope (as discussed above) Fallout 3 and Fallout: New Vegas feature unkillable children. Upon taking normally mortal damage, they'll fall unconscious for a while before getting back up (similar to what plot-critical NPCs do.) This can be a problem for sociopath characters in Little Lamplight as it's entirely populated by children and necessary to pass through since it forces you into a diplomatic solution.
The heroes of the second Onimusha game manage to save a baby that has been kidnapped by demons. The baby's crying, however, gives one of the secondary characters a flashback to how he was unable to save his own baby daughter from a fire.
In Clock Tower 3, one of the first scenes is a young girl, around ten or eleven, being viciously beaten to death with a sledge hammer.
Fire Emblem: Genealogy of the Holy War has an empire that believes that children are only good as conscripts or to sacrifice to the Sealed Evil in a Can (makes you wonder what they would have done in a generation or two). The games final bosses also consist of three children and a creepy old guy. One child is brainwashed and can be recruited while another is possessed by Sealed Evil in a Can but the third is a genuinely good person who has fallen in love with the aforementioned possessed demon child and is only fighting you after you killed her entire family. Doesn't help that the main antaognist of the second generation doing all this killing is a child himself.
For the series in general, while you'll almost never see children among the enemy's ranks, enemy units hold no pretense when it comes to killing your army's Child Soldiers, and since they typically have low HP compared to adult units, they often have to be guarded by someone with more endurance.
In two of the four endings of Splatterhouse 3, Rick's son is killed.
Resident Evil 4 leaves hints of what happened to the children of the village. Early in the game a very small skeletal hand can be found on a bench near an impaled woman, and the ending credits shows children in the village, the last shot showing a child playing while a ganado sharpens a knife.
The booklet that came with the Biohazard 4 Incubate DVD confirms that the children were injected with the same parasites as the adults, but their small bodies were unable to contain them.
Averted in Psychonauts, though she's only a thought in a paranoid schizophrenic's mind:
Rainbow Squirt:[pointing gun] Freeze! Don't come any closer! I'll never tell you the location of the Milkman! Never! Raz: Okay, let's all just settle down and talk— [She throws herself out the window.] The Men in Black: Where is the Milkman? Who is the Milkman? What is the mission of the Milkman? Rainbow Squirt: [dying] Come closer...and I'll tell you... [Her cookie box explodes, blowing them all away.] Raz: Glad I never bought any of those.
Also, averted more seriously, in one of Milla Vodello's memory vaults: Before joining the Psychonauts, she was in charge of an orphanage, which burned down with the children inside, while she was unable to save them. This vault is easy to miss, as it is locked away in a far corner of her mind, presumably her way of trying to forget it and move on, despite the fairly strong implication that she's still haunted by the memory.
In Fable II, an early quest has you attempting to rescue a man's son from a gang of hobbes. You don't reach the child in time, and he has been turned into a hobbe, which you then kill. You never actually saw the child as a human, and he looks like an ordinary hobbe, so it's a lot less heartrending than if you had.
In the "They Hunger" mod for Half-Life, in the hospital, you hear a baby crying. When you get to the room, near a window and press the button to call for the nurse, you see the nurse open the window, and it's revealed she was zombified. When you take a look at the baby crib, you see a blanket and bloodstains.
In Resident Evil 2, it is possible to witness the death of Sherry Birkin, a twelve-year old, if the player allows her to take too much damage.
Which is rather hard to do, as the kid takes more damage than Ada Wong, superspy, can. Kid drinks her milk.
In Dead Space, babies have been transformed into hideous monstrosities that are still recognizable as babies. Protagonist Isaac can kill them by shooting them, or, if they latch on to his face, ripping them off, power-bombing them to the ground, and then punting them. There's an achievement for doing it enough times.
The sequel cranks the aversion up to eleven. Not only are there infected kids running amok, but there are also EXPLODING BABIES. One poor social worker tries to empathise with a cooing one. Guess how you first figure out the exploding part.. Messed up as he is, Issac has no explicit qualms about cutting off their limbs and stomping their torsos. On the plus side, they are easier to defeat.
Which leads to more than a few chuckles when you say to yourself, "Ready Issac? Kick the Baby!"
Doom 3 also had mutated babies with wings as monsters, appropriately called "cherubs".
Left 4 Dead does not have children as humans or zombies anywhere in the game, but it does say that many died during the crisis. Inside the church in the end of Chapter 3 on the Death Toll campaign there are written memorials to dead family, friends, and pets with their birthdays and days of death listed under them. A lot of the people listed as killed end up being less than 5-years-old.
In Siren (also known as Forbidden Siren), the characters of Miyako and Tomoko, both of whom are aged 14 (though the instruction manual of the US release states their ages as 17), meet their untimely ends: Miyako is sacrificed in a ritual (although her spirit lives on), and Tomoko transforms into one of the undead Shibito. It is also possible to see them both die if they sustain too much damage in-game. However, ten-year old Harumi of the same game is never even seen being attacked if she is discovered by a Shibito, so perhaps the game developers didn't want to go too far.
Metal Gear 2 for the MSX2 actually allows the player to shoot the small children wandering around Zanzibarland. Doing so will cause the player to be penalized with loss of health.
Averted in Stuntman: Ignition. In the trailer for the film Aftershock — one of the films you do stunts for — the first scene features firemen trying to get a little girl's cat out of a tree... when an enormous wave of lava flows through and kills all of them. The little girl is conveniently off-camera when this happens, but...
Softened somewhat by the fact that it's entirely fictional, even within the context of the game it happens in.
Somewhat averted in Dragon Age: Origins. For the most part, this trope is played straight; children don't generally show up in any combat situations and you can't randomly slaughter most of the children you do see. But there are storyline-related exceptions where children DO die. In the Human Noble origin, the Player Character's endearingly cute nephew is killed alongside his mother by Arl Howe's men. In Redcliffe, any Player Character may opt to slay a demon-possessed child. And in Orzammar, a PC can convince a mother to abandon her casteless child in the Deep Roads to starve to death or worse.
Let's be fair, most games where you play as a kid avert this trope (to maintain challenge), though usually only for that playable character, and only when you mess up, rather than in the story.
In Dark Fall: Lost Souls, one of the haunted rooms at the hotel contains a cradle, from which the cries of an infant can be heard. Followed by the sound of a bomb exploding, which presumably killed the infant when the hotel got bombed in World War II.
Almost all the characters in Rule of Rose are children, but the game masterfully skirts around the issue by hinting, rather than showing the horrors which they endure. Not one dead child is actually shown, but it's made painfully clear that many end up dead in the course of the story.
Averted in some places in Golden Sun: Dark Dawn, as a sign that the stakes have been raised and the Grave Eclipse is deathly serious.
If you go for the Crystallux summon in the Belinsk Opera House, a cute violinist girl tries to defend her friend the chandelier-dragon from a trio of Eclipse monsters, one of which casually crushes her. Matthew avenges her as the dragon bids her goodbye.
Oddly enough, played straight (maybe) if you return to Kaocho. Several of the rotting corpses you find there, when Spirit Sensed, mention that the kids were all evacuated to the palace, which is shut tight. How straight this plays it, considering that Kaocho Palace is not exactly a fortress and the king's a war-hungry narcissist, is up for debate.
There are no children at all in the Postal games, because even the game designers felt that putting children into a world where the player can kill everyone would be horribly wrong. However, dogs and cats are open targets starting in Postal 2 and Postal 3 promises even more. Cats may be used as pistol silencers in Postal 2 by shoving a pistol up the cat's butt.
The trope is played around with in the first game. The final level of the game is at a school, and the Postal Dude appears right in front of a playground full of kids. He then proceeds to open fire on them, but doesn't hit anything, nor do the kids even react, suggesting that they might be some kind of hallucination. The Postal Dude then suffers a Villainous BSOD and is captured right after.
Consider the fate of Mobliz in Final Fantasy VI. Somehow not one of the town's adults survives the end of the world, yet every single one of the children does. The explanation given is that all the adults perished trying to save their children, but still...
Averted and played straight in RuneScape. There are no attackable human, elf or troll children, but players can freely slaughter gnome children (another of the civilised races in game), calves and baby dragons.
The "hero" of Peasant's Quest throws a baby into a river, nearly trades it for pills and generally abuses it. The baby never dies, and a text part once it runs away permanently tells you it grows up reasonably well-adjusted, but he eventually "develops a severe mead problem and blames you for never being there."
You can also leave the baby in a well, but if you leave the area, the game will scold you for trying to ditch the baby, then kill you.
Ambiguous in Xenoblade. Near the end of the game, the pure-blooded High Entia are turned into monsters, and for all intents and purposes killed. You can look at the affinity chart screen after this point, and many of the High Entia NPCs have their icons darkened indicating they've been transformed. This includes two young children. However, unlike many of the adults, there isn't a quest that opens up after this point requiring you to kill the monsters that the kids turned into. There's another quest that indicates that there may be a way to return the transformed people to normal, so it's up to the player's imagination whether the children will live or die.
Something of an aversion in Tales of Symphonia. Governor-General Dorr's young daughter is killed and replaced by a lookalike demon thing. It's averted because the death supposedly happens before the game starts, so we never see the death or the corpse, and we do not interact with the real girl before she dies.