Please don't list this on a work's page as a trope. Examples can go on the work's YMMV tab.
Nightmare Fuel: Eternal Darkness
The first M-rated game ever published by Nintendonote this is a mistake; Perfect Dark holds that title pushed gamers to the edge of sanity and back. A legitly scary game, the sole purpose this game was made was to fuck with you. Your head randomly falling off, misplacement and, of course, the legendary DOS prompt. Genius. The lower your sanity meter goes, the more screwed up the game gets. This truly is a psychological thriller.
That quote says it all. Perhaps the game did its job too well, as these entries will attest.
The hallucination of a dead Alex in the bathtub.
The bust of Brother Paul Luther in the upstairs hall turning its head as you walk by may be the creepiest thing in the whole game. Which gets even weirder as you encounter the same statues in the level where you play as him!
Frantic knocking on the other side of a door, which you open...to find that no one is there.
Blood running down in streams from an idyllic landscape painting.
The idyllic landscape painting that turns into a desolate hellscape.
The painting of the Roivas family tree in the library. Look closely enough at the right side. The only family tree you'll see that has someone hanging from it.
Casting a healing spell, and exploding from the waist up.
Walking along, when splat - a splash of blood on the floor a few feet behind you. Seconds later, splat, another gallon of gore falls from the ceiling, this time a bit closer. Splat. Splat. Splat...
Then there are the little hints that Alex's grandfather's ghost may not be exactly what he seems...
The vast quantities of Bonethieves present in the World War 1 level, combined with the eerie background music and dead (or dying) bodies piled everywhere inside the haunted church.
According to Max's autopsy of a Xel'lotath bonethief, the victim they inhabit remains conscious but powerless: "While our souls are pushed into the corners of our skulls, watching as our hands do tasks that we have no control over!" Of course, Max was quite thoroughly insane, and bonethieves seemed to be the primary reason for it, so he might have mentally exaggerated them. But if he did, it couldn't have been by much.
Bonethieves are very much in-universe Nightmare Fuel as well. Watching a Bonethief burst out of its host carves huge chunks out of your sanity meter.
Picking up the Tome of Eternal Darkness with most of the side characters. You walk over a stone bridge carved with a multitude of human faces...which then begin screaming in agony as a giant skeletal hand opens up to offer you a book bound in human skin. Sounds comedically over-the-top, right? It's not.
Collecting weapons and ammunition as Alex, long before you actually need them, is unsettling to say the least. The whole point of Chekhov's Gunis to fire it, right? And the longer you carry it around without firing it, the morewrongthings seem. In fact, the game would've been even scarier if it had ended with Alex never using any of those weapons.
"I can't get the blood out!"
Just the idea of Mantorok. A colossal fleshy mass, a sea of maws and eyeballs, nailed to the floor by huge stone columns in a lightless chamber beneath an ancient, forgotten Cambodian temple, wasting away in the darkness over hundreds of years, scheming, plotting, manipulating human history in order to get back at the rival Ancients that imprisoned him.
Not to mention that if you inspect the room, it's apparently covered with a thick layer of effluvial grime that the monsterous flesh god has been belching out for milennia.
Consider it this way- Mantorok is a giant, amorphous mass masquerading as a Cambodian fertility diety. His influence has destroyed the region around him, leaving it uninhabitable (And causing who knows what other madness). And the worst part? He's your only hope for saving the world from something WORSE.
Any time Xel'lotath speaks. One voice is imperious, arrogant, exuberant...but the other is a hissing near-whisper, paranoid, delusional, constantly questioning her own plans or the loyalty of her minions. It's like Gollum/Sméagol cranked up to 11.
The sizes of the zombies- the smaller ones can't be anything but the skeletons of children. Probably the scariest subtle detail in the whole game.
Is there any part of the game that isn't nightmare fuel? The scariest part is the Xel'lotath Lesser Guardians. Empty husks that resemble headless conjoined twins. How does it move? How does it survive? How does it cast Magickal Attack with no mouth to say the words? How does it know where you are to attack you when it has no sense organs whatsoever?
"Oh... oh gibbering insanity wrought in flesh as though an artist had sculpted it! Created from nothing by their mistress Xel'lotath, a canvas as grotesque as any! Their bodies made no sense - no heads, no organs - an empty husk devoid of the trappings of nature... But it walked... it sang... it shrieked!!! A mockery of reason, both natural and mental! A blasphemy from beyond the Veil!!!The veil has opened!! And we should NOT see beyond! We... we weren't meant to... never, ever meant to... Oh, give us the blessing of ignorance, the happiness of oblivion... Innocence can only be tainted, never returned!"
The Sanity Meter. Whenever your character would come across a monster or something scary, their sanity meter would shrink a little and could only be raised by performing "finishing moves" on the enemies. The lower your meter went, the more screwed up things your character would hallucinate. When it got near the bottom, the game would start to fuck with not only your character but you. Such things include:
Trying to load or save your game only for the game to tell you it instead is going to erase your saved data.
Walking into a room and slowly having your limbs fall off.
Casting a healing spell only to have your body explode.
Walls bleeding, corpses falling from the sky, seeing enemies that aren't there.
The video game equivalent of "standing in front of everyone naked", you would enter a new room and suddenly have no weapons, being unable to do anything but watch your character die.
A variation of this would have you move into the new room, where a dozen-odd zombies were waiting inches away to immediately tear you to shreds, with the GameCube dialogue popping up stating that the controller was unplugged.
Additionally, there are some fairly rare but incredibly unsettling sanity effects, such as shadow creatures that split from the wall and quickly fade away when the camera view turns, as well as a misfire with Max's flintlock pistol during reloading that results in accidental suicide.
Also, the bugs on the inside of the screen.
By fact the creepiest sanity effect is one that everyone experiences: after you finish playing as the third "side" character, the game cuts to Alex in the library reading the Tome of Eternal Darkness, and then cuts to a screen telling you that you've finished the demo. This screen will stay there for a good fifteen seconds, just long enough for you to get pissed off that you got a gimped version of the game, and then BOOM! "This...isn't...happening!"
Another creepy part of the game is when you're playing as an aide to Charlemagne early in the game. You get afflicted with a spell at the beginning of the chapter, and as you continue playing, you're slowly turned into an undead abomination. By the end of the chapter, you reach the final room, only to find that you failed in your quest to protect Charlemagne, and then you die.
But that's not the end of it! OH no! Another character, Paul the friar, ends up in the same church in a later chapter. You enter the room where the aide died before, and you hear a voice hissing "Charlemagne...". It's the aide that you played before, still "alive" after 671 years of torment as a zombie. There's at least some solace to be had, though: after Paul kills the zombie, he realizes what happened and prays for the poor guy's soul. It's not much solace!
Once hit with that spell, the character could not die except when dictated by the story. Emptying the player's health bar only resulted in the character getting back up. His fate was so decided by the Powers That Be that he was unable to even die of his own accord.
After defeating Pious Augustus and his chosen Ancient, Alex experiences a moment's clairvoyance, where she sees the counter-Ancient she released rape humanity something bad. The visions are seen in flashing, rapid still images, and which Ancient has the least horrible designs for humanity is anyone's guess. To elaborate...
In a world where Chattur'gha reigns, his creatures run wild over the earth, turning it into a blood-soaked wasteland of flayed corpses where humanity is reduced to prey for the Ancient's creatures. Those unfortunate to be caught will be force-marched across the desert to crude execution platforms, where they get hanged and butchered in droves. Thus is the ultimate fate of humanity under Chattur'gha...to be nothing more than cattle, sating the savage appetites of its horrific creatures.
Should Ulyaoth come to power, the human race will be taken to what can only be described as an Eternal Engine with Alien Geometries that exists in a fathomless void, bound by energy shackles to floating platforms that deliver them to surging energy furnaces. Thus is the ultimate fate of humanity under Ulyaoth...to be little more than batteries for Ulyaoth's incomprehensible machinations.
If Xel'lotath were to emerge into our reality unchecked, humankind would be enslaved and forced to construct eerie cylindrical monoliths, each one adorned with a sinister emerald eye that seems almost alive. To make matters worse, it's implied that the construction of each monolith involves a ritual in which the slaves are forced to brutalize each other, ultimately driving themselves insane before beheading themselves...and then coming back to life, holding their severed heads and continuing to serve! Thus is the ultimate fate of humanity under Xel'lotath...to be reduced to slaves serving the insane whims of a Mad Goddess until their own sanity is lost forever.
Anthony and Ellia both remain hundreds of years imprisoned in small alcoves within their own rotting bodies. And I Must Scream suddenly seems so small...
A case of Talking To Herself with Alex takes a turn for the worse when you realize who else Jennifer Hale is voicing. Yes, Alex and one of Xel'lotath's voices are done by the same person.
The Edgar Allan Poe quote at the start of the game certainly sets the tone for the rest of it, and it's kind of creepy how it precedes everything, including the title screen and logos, to be the very first thing you see and hear when you start up the game.
In the PAL version at least, when you select 50 or 60 Hz on that screen, it briefly corrupts and the voice stops, giving the impression that you made the wrong choice. The game works fine afterwards though. Whether it is deliberate or not, it's a very effective first scare.
Characters will tend to talk and gibber to themselves with their sanity depleted, in personalized ways. While whispering or whimpering on any of the protagonists is standard enough, some of the distinct ones, such as Anthony sobbing "Dying... I need... help me..." or Paul's screaming unprompted at the top of his lungs, can be unnerving.
During the opening movie of the game, one of the first things you see is an animated skeleton staring directly at the screen. Nice opening for "kid-friendly" Nintendo, eh?