Despite being in ASCII and not outwardly scary, this game is full of NightmareFuel, all of it being mostly FridgeHorror. If your fortress hasn't produced ''some'' sort of nightmare fuel by the time you're done with any given fort, you're ''clearly'' doing something wrong.
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* The players. The bloody players. Maternal armor: "It's been a long time now since I realized that dorfs bring their babies into battle with them. It's been a slightly shorter time since I started recruiting only female dorfs into my military, and making sure they each had enough time to mill about with male dorfs to be constantly nursing."
** "[[http://www.bay12forums.com/smf/index.php?topic=91093.msg2532587#msg2532587 Im beginning to wonder if the goblins arent trying to do the children a favor.]]" From a thread which suggested to raise dwarf children by throwing them into pit with 12 years' worth of food and 12 year's worth of feral dogs. [[http://www.reddit.com/r/dwarffortress/comments/umaei/so_apparently_thats_how_goblin_snatchers_look_at/ Apparently they are doing them a favour.]]
*** It should be noted that the children are put into such a situation because [[TrainingFromHell 12 years of constant fighting with the feral dogs]] will, in the event of survival, produce super-dwarvenly tough and super soldiers for instant conscription into the dwarven army.
** It is possible for a woman to accidentally hit an enemy with her baby.
* Pretty much everything in the new medical system can cause this.
** The new health/medical system has had its share of bugs, which is its own cause of NightmareFuel. Like your dwarf getting his legs chopped off. Then seeing him still making his way around the fortress doing jobs a few months later, with his legs still missing.
** Or when diagnostics was still horribly broken and a dwarf would spend literally months lying on the floor bleeding out while the doctor totally ignored him. The solution? Build a spike trap under him and continue to spike him until the doctor took notice of one of his new injuries and dragged him to the hospital or he died.
*** Speaking of diagnosis issues, [[http://www.bay12forums.com/smf/index.php?topic=89877.msg2483388#msg2483388 how about the dwarf whose cut on his arm was diagnosed as rotting lungs]]? The surgeon then removed the dwarf's lungs...the dwarf, obviously, did not survive. Possibly the worst part? This was an experiment to see what happens when you assign a dwarf with no diagnosis skill to be the chief medical dwarf.
*** Even worse, a vampire doctor, just imagine the implications...
* Pretty much any player interaction with lava has a good chance of creating this.
** Bugs especially, as they have a tendency to create things like perpetually burning puppies or unkillable blizzard men who are still wading through the stuff even as their fat boils off through their eye sockets (yes boiling fat is quantified by the game).
** The cherry on top is that after its over your engravers are liable to fill your entire fortress with procedurally generated carvings of people melting.
* ''[[DisasterDominoes Tantrum spirals]]''.
** Urist [=McCatlady's=] cat dies. [=McCatlady=] proceeds to break Urist [=McLumberjack's=] favorite table. Urist [=McLumberjack=] [[DisproportionateRetribution proceeds to murder three dwarves.]] The families of the dead then murder others/break things/begin to riot. Repeat. Once a Tantrum Spiral gains momentum, nothing save for flooding the fort with lava and leaving a few survivors tends to work.
* Procedurally generated Forgotten Beasts. Say goodbye to plain old vanilla [[CombatTentacles tentacle demons]], say hello to acid-breathing elephants made out of barf with three eyes and six legs. [[note]]To explain, these are usually based on a normal animal with one or two unusual feature (three eyes, one eye, pair of wings, horns, etc), a glob of some random material (vapor, vomit, blood, etc) with one or two different appendages (like tails or wings), or a quadruped/biped made of some sort of metal with some extra features (again, mostly tails or wings).[[/note]] Some can be quite unnerving:
** A giant frog-like creature made out of vomit with exposed circulatory system that spits a poison that causes your dwarves' skin to melt ''and'' -- thanks to implementation of "syndromes" -- is ''also transmissible''? Geh.
** A huge eyeless cicada [[DepartmentOfRedundancyDepartment with no eyes]] and branching antennae and a red exoskeleton that spits webs!!
** "[[http://www.bay12forums.com/smf/index.php?topic=67410 A penguin brute, who happens to lack a mouth, has a tail, and "it knows and intones the names of all it encounters".]]"
--->"Wait, how does it intone names without a mouth?"
--->"I don't know, but it still does. ''That's the creepiest part.''"
** The blood of certain Forgotten Beasts causes body parts it comes in contact with to rot instantly. Cue several dwarves roaming the halls of your fortress in a daze, bleeding and spewing miasma as their bodies rot -- while they're still alive -- before they swiftly suffocate and die. Or sometimes they don't swiftly suffocate and die. Sometimes they survive, but all the flesh melts off their feet... but they still have feet and are still walking around despite the fact the rot is slowly moving up to the legs now.
** Be afraid. Be very afraid. [[http://i.imgur.com/ykWrR.png The Ass Demons are out there.]]
** A Zinc quadruped with gas that causes rapid bleeding out. It had to be taken down in hand-to-hand.
** Sometimes it's possible to get creatures that ''[[OurMonstersAreWeird don't make any sense]]'', like [[OxymoronicBeing six-legged quadrupeds]] made of salt that swim in water and magma.
*** Perhaps more horrifying still, the fandom is capable of creating ''[[BrownNote images]]'' [[BrownNote of these creatures]]. Images that ''make sense''. That includes a rather nonchalant-looking box-shelled ''beakless woodpecker'' with the ability to unroll webbing from a line on it's back.
* A lot of the underground wildlife in the new version, too. [[DemonicSpiders Giant cave spiders]] were bad enough...
-->A medium-sized monster walking on two clawed legs. It has two mouths on the ends of a pair of tentacles. It uses its mouths to digest its victims with acid and rows of razor-like teeth.
:: Some of them are blatant CaptainErsatz versions of DungeonsAndDragons monsters, but many of those are excellent NightmareFuel already. Vargouilles/Hungry heads, anyone?
* Speaking of demons... [[spoiler:You can dig into hell now.]]
* {{Boatmurdered}}. In the end, only one sane dwarf was left, who was wearing both Adamantine Chainmail ''and'' Plate Armour to protect him from the insanity. Everyone else was on a murderous rampage or on fire from burning puppy bodies. The place was a veritable nightmare fuel refinery. Here's a quote straight from one of the players logs.
-->"At this point, we have somehow managed to create [=*=]THE* root of evil in the dwarven universe. Here is what it must look like from the mountainhomes:
-->1) Dwarves go to Boatmurdered and disappear.
-->2) Lava comes out of Boatmurdered and destroys the surrounding environment no less than three times a year.
-->3) A maniacal dwarven supervillian comes out of Boatmurdered and goes on a killing spree.

-->Shit, there are probably entire fucking sagas that are being sung about the evil fortress of damnation known as Boatmurdered."

** The wildlife around Boatmurdered counts as well:
---> "''The trumpeting! THE TRUMPETING!''"
** The MadnessMantra of the aforementioned armoured dwarf.
--> [[KillItWithFire "All burn..."]]
* When you've DugTooDeep, specifically by [[spoiler:following an Adamantine vein until it gets hollow]], the game makes it very, ''very'' clear you're in for some [[UnusualEuphemism Fun]].
--> '''Horrifying screams comes from the darkness below!'''
** Hooray! The [[UnusualEuphemism Circus]] is here!
* Evil biomes. The werewolves, ogres and masses of undead are bad enough, but hey, you can handle it, even when the fish slither out of their pools like something out of [[{{Manga/Gyo}} Gyo]]. Then you notice that all the trees and shrubs are dead, too. Then you notice this doesn't stop them from growing. The ''Savage'' Evil biomes are called "Terrifying" for a reason.
** As for version 31.19 the Evil biomes became more creepy by sporting grass made out of fingers and Eyes - and yes it blinks at you.
** Then one of your dwarfs gets possessed and uses some of this 'wood', the bones of one of the 'animals', and a seemingly normal chunk of basalt to make a statue. [[NightmareRetardant Of cheese.]]
** With the 34.01 release, evil biomes are much, MUCH worse, with sickening sludge raining down from the sky on your dwarves and spreading disease all over the surface, and evil mists that make everything they envelop die in horrible, horrible ways. Also, nothing stays dead. Not even butchered animals' skins or severed limbs. Not even if you've already killed them several times. They'll be back again. Then there are the "thralls" and "husks" - creatures that have been turned against all life by evil fog. How scary are they? Oh, they're only so strong that they'll kill [[spoiler:''an entire fucking horde of demons while outnumbered several times over.'']]
* Occasionally, Toady's comments in the dev log about the more gory moments in testing.
-->"During the test (a 20 sword free-for-all), a guy got stabbed in the lower body twice, his guts popped out, and then a third guy came up and severed his exposed guts, so that all seems to be working."
-->"In other news, the dwarf with the ''boiling gold blood''..."
* A recent forum thread (can't find link) was about a player's military encountering a Forgotten Beast that caused their skin and eyes to rot and permanently paralyzed their peripheral nervous system. Thanks to his effective medical staff the majority of them failed to die from either the rot or any subsequent infection. The result was an eyeless, skinless, Legendary military that, thanks to the nerve paralysis, felt no pain. This either belongs here or on the [=CMOA=] page. Probably both.
** [[http://www.bay12forums.com/smf/index.php?topic=90937.0 This]].
--->"Let's expose our military to zombie-dust so they can't feel pain. They don't NEED skin."
* VideoGame/DwarfFortress players are not exactly the picture of sanity and/or morality, and they're [[CardCarryingVillain well aware]] [[MadHatter of it]]. They'll acknowledge how fucked up it is to have a discussion about the best way to capture mermaids in order to start breeding an endless supply to kill and harvest the ever valuable bones from. But they ''will'' discuss it.
** The worst part about this... is that money isn't all that important in DF... DF slowly turns players into Dwarves by having them horde an increasingly valuable treasure for no reason other than they can. Mermaid bones were valuable... but mostly pointless... they did it... simply for the challenge.
** The ''worst'' part is really imagine a scheme to capture mermaids, chain them up and force them to produce young, then "air-drown" the young to butcher them for bones.
*** The best part was that Toady promptly nerfed the value of mermaid bones because [[MyGodWhatHaveIDone he was so horrified by this]].
** There was also the "Most evil/horrific thing you've ever done" thread on the Bay 12 Games forum which was deleted because somebody "[[MoralEventHorizon won]]". And it was not the story of the dwarf who broke a child's arms and legs, proceeded to slowly beat the parents to death right in front of the child and then beat the child to death with the corpse of its mother.
*** Just in case you're REALLY curious, it involved [[spoiler:modding in genitals in order to [[RapeAsDrama rape an elven child to death]].]]
* How about the injuries?!? When your arm gets ripped off, what do you think? Well, in Dwarf Fortress, Dwarves just keep walking around, leaving a GODDAMN blood trail on the floor.
* Bronze Colossi. Huge, nightmarishly fast, and unimaginably strong. Oh, and damn near unkillable. Large parties of adventurers have been reduced to screaming, mangled piles of agony by these monsters. They tend to grab their victims, put their limbs in a lock, then break them. The really don't need to: they could kill most players just by grabbing their head, and pinching. Consider that for a second: they could kill you instantly, but instead they toy with you until they tire of you, then kill you.
** More importantly, they could just strangle you to death (there's pretty much no way you could break their grip), or gouge out your eyes, or many of the other nastier wrestle moves. Instead, they break your arms and legs before punching you to death. [[FridgeHorror They don't blind you, because they want to see the look in your eyes as you die, and they don't strangle you because they want to hear you scream...]]
* Giant Cave Spiders. Not only there's the whole BigCreepyCrawlies and GiantSpider feel, but they kill dwarves in horrific days.
** Let's elaborate. GCS throws web. Dwarf gets immobilized by web. Dwarf gets bitten by GCS, therefore getting GCS neurotoxin in it's blood, who will start paralysis on the dwarf. GCS continues to bite dwarf, who is still conscious but paralyzed. Dwarf loses blood, gets closer to asphyxiation due to muscle failure. Repeat this a hundred times, until the dwarf dies of blood loss or asphyxiation.
** GCS generally take '''days''' to kill a dwarf in this way. CruelAndUnusualDeath anyone ? Ugh.
* Some creatures that were modded in fit this trope quite well, such as the Holistic Spawn from [[LetsPlay Syrupleaf]], as seen [[http://lparchive.org/Dwarf-Fortress-Syrupleaf/Update%2015/4-holistic.png here]].
* From Toady One's devlog, with emphasis added: "I tried the butcher command in the arena, and the necromancer managed to raise both a skeleton and ''a walking hollow skin''... which I suppose I'll keep since it makes about as much sense as a walking skeleton. So... keep the necromancer away from your raw skin stockpiles, [[EvilLaugh he he he]]." This is why vegetarian forts are recommended when embarking in evil biomes.
** Toady One's devlog is a fountain of this. To date, he has mentioned [[VertebrateWithExtraLimbs Dwarves specifically designed with extra limbs]] (to test item retrieval needs); Dwarves being mutilated on impact while in, and being run over with their innards dragging behind minecarts; the previously mentioned Necromancy... the list goes on and on.
* A topic on the forums recently was how a dorf baby was killed during a siege and it came back as a ghost. But the ghost baby was still being carried by his grieving mother. Imagine walking down the halls of a fortress and just seeing a mother, in a corner, crying and coddling a cooing transparent baby.
** And on that note,
--> She was attacked by own dead child lately.
* The 2012 release brings us lots of BigCreepyCrawlies, like giant brown recluses and giant mosquitoes that like to swarm your fort and suck your dwarves dry. And one release had a bug that caused hundreds of giant mosquitoes to spawn at once.
* Yaks. ''Bloody horrifying Yaks.'' '''''[[Webcomic/SluggyFreelance Canadian Ninja Yaks]]'''''. If you have yaks on an Evil biome, they will. Murderate. You. Smoke zombies? More like [[Webcomic/GirlGenius smoke knights]]. Who will track down and kill ''every last one of your dorfs''.
* Also-we finally have something that terrifies the players-which if you've been reading this page, is really something: [[TheUndead Night]] [[TheVirus Creatures]]. To put it simply: Vampires get a bonus ''200'' [[note]]That is, their strength, toughness and agility are ''doubled''[[/note]] [[TookALevelInBadass to their]] [[MadeOfIron physical stats]], Werebeasts have a HealingFactor that fixes ''everything'', including limbs, and Necromancers can call a ZombieApocalypse with a thought. And not one of them ages or gets hungry or thirsty or tired (beyond the vampire's need for blood, of course). Imagine trying to fight these guys.
** Necromancers are bad enough, but if one is killed in Fortress mode and isn't [[DueToTheDead interred or memorialized properly]], they, like everyone else, can become a ghost to come back and haunt you. What's ''really'' creepy is that they '''can still raise corpses'''... including their own. And then there's the [[BlatantLies nice little]] quirk of werebeast limbs raised by necromancers regenerating ''entire creatures'' on a full moon.
** As of v.40, undead from necromancer sieges carry ''armour and weapons''. Let the sheer terror of that thought work your way into the brain. There are several stories of a single undead swordsman annihilating multiple squads by himself. On the bright side, zombies can now be [[KillItWithFire killed with magma]].
* The GIANT SPONGE. They seem utterly mundane and harmless until you realize... they have only one body part, no brain, and no blood. Edged weapons only tear it, and blunt weapons serve no purpose but make it mad. And despite seemingly being unable to move, it can push at a dwarf and kill it instantly. Fire cannot kill it, nor can magma. Not even an army of a thousand bronze colossi could destroy this creature. Only through air-drowning it or encasing it in solid stone or ice can it be destroyed. And gods help you if you come across a zombie giant sponge; they're even harder to kill since they don't have to breathe.
** Giant sponge husks anyone?
** As someone on the forums described them, "They have no nervous system. All they can feel is ''hate''."
** Giant sponges are killable as of version 0.40.01.
* Bogeymen, in adventure mode. Don't walk alone in the wilderness at night. "You hear a loud cackle." And then, it runs out and takes you... Note: Bogeymen aren't impossible to beat, if you have proper training and have decent fighting tactics.
* The Ultimate Nightmare Fuel lays outside the game though. AuthorExistenceFailure is every DF fan's worst nightmare.
** Toady has [[TheDevTeamThinksOfEverything taken even that into account]] and made arrangements for the code to be open sourced if the worst happens -- ''[[MakeItLookLikeAnAccident unless it looks like foul play]] was involved''.
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