The title of the series alone speaks volumes: The Metal Gear is absurdly terrifying once you realize what it can do. The thing launches nukes that could reduce a city to ash in seconds, but unlike a missile silo, it moves. And if you try to shut it down, it fights back. It can launch its nukes from anywhere on Earth... and they're completely undetectable by radar. If these things really existed, we would have to live with the knowledge that nukes could fall from the sky at any moment without warning. Most games would leave this as simple Fridge Horror, but Kojima is absolutely blatant about Metal Gear's implications because, well... Some Anvils Need to Be Dropped.
Many came to dread the "Game Over" screens in Metal Gear Solid, where a random character will scream for Snake after his death ("Snake, what happened? Snake?! SNAAAAAAAKE!!").
Of course, this is a subjective trope for a reason.
Then again, the cries in the original Metal Gear Solid are probably the worst in this regard. Hearing Mei Ling or Naomi scream SNAAAAKE! with utter anguish is heartbreaking and terrifying in how real the voiceover feels.
MGS4's game over is even more disturbing: in addition to the "Snake? SNAAAAKE?!!" line, the most vital scenes from the game's story up to that point flash rapidly on screen as Snake dies, as if to remind the player what was at stake.
Plus, the music that plays during the game over is so fast paced, it makes it more nerve-racking.
Gray Fox: Imagine dying, then waking up in a painful exoskeleton, and experimented on repeatedly, with your memories coming and going and the only sensation you can ever have is pain, the poor, poor guy.
Imagine a man who can turn invisible at will, deflect bullets with a spin blade spin who can suddenly and terribly go Axe Crazy while you are unable to land a hit. You never felt any pity for any Mooks than the ones he slaughters just before you fight him.
No matter how badly Raiden is looked down on by the fandom, he really did not deserve what happened to him between MGS2 and MGS4. He was eventually kidnapped and put through a similar stage of torture and experimentation that Gray Fox has been through, only worse - he loses everything below his upper jaw and gets replaced with cybernetic parts. Fortunately it seemed that he hasn't suffer the same psychological trauma that Gray Fox did.
And for those who feel sorry for the poor guy, at the end of the game you find out that he has had surgery to look human again, but there are still marks from the cybernetics visible.
Vamp is a Depraved Bisexual with the ability to jump from any place, anywhere with great skill with that knife of his, an extreme blood-addiction to the point where he even ripped the throat out of a SEAL, and he can pin you into place by using your own shadow.
Don't forget the fact that he was caught in a church bombing, pierced by a crucifix, forced to lie in the rubble next to his dead parents, and only survived by drinking their blood. Fun times!
Metal Gear Solid 3
Getting caught by a gavial underwater is a very effective reminder of why crocodiles are so damn terrifying in Real Life.
After saving the game after Snake ends up in prison in MGS3, you expect it to load up at the prison where you left off. Instead, you are treated to the most bizarre sequence ever, where the entire screen was black and white, you wielded a big sword, were capable of gravity defying stunts, and zombies came lumbering at you endlessly that spewed impractical amounts of blood after you sliced through them, something that might have come out of a machine that mixed Resident Evil with Ninja Gaiden. The sheer unexpectedness of such was freaky; even if you weren't necessarily scared by the zombies, you'd probably be wondering if your MGS3 disc is faulty.
Several of the bosses count. There's The Pain, who attacks using thousands of bees, and is, himself, a living beehive. The Fear has a long, forked tongue, and double-jointed elbows that allow him to scurry up and down trees in a very creepy manner. The End's battle is a long, drawn-out sniper battle, and though tense, isn't scary... though if you sit around in first-person view for too long, he'll sneak around right behind you and shoot you, which is sure to make some people jump. The Fury stalks you around in a series of dark corridors, with slow, heavy footsteps; hearing those footsteps running full-speed at you can be freaky. And, finally, the worst of the bunch, there's The Sorrow, who comes to you during a near-death experience, and takes you on a nightmarish trip through a river filled with dead fish and human skulls. Disturbing pictures occasionally fill the screen, accompanied with a scream. You must confront everyone whose lives you've ended so far, too. They're depicted in the way you killed them: If you shot a guy in the leg, his ghost will be limping. If you slit his throat, his head will be hanging back, his neck spurting blood as he shambles towards you. If you've been taking the Rambo approach to the game, indiscriminately gunning down guards and innocent scientists alike, this sequence can be quite gut-wrenching, as you'll be facing down dozens, even hundreds, of angry ghosts.
Not to mention his speech. Firstly, The Sorrow himself has that deliberately quiet tone that suggests he's absolutely furiously angry (more so than The Fury, who just overacts a bit) as he admonishes Snake; "The dead...are not...silent." As he finishes his speech, a bloody tear runs down his cheek, a gunshot sounds out, and one lens of his glasses shatters. Shiver.
He mentions 'you will be killed by your own sons.' If you have slaughtered enough guards, you get a nifty picture of Solid shooting Naked as one of the images you can get.
Then you have the sequence itself, with screams and whimpers of 'I'm worthless now!' as the dead try to grab at Snake. Creepier still, though, is the sight of The End. He's floating face-down in the river, and still somehow drifts towards you.
"Rawk! Grandpa, grandpa!" Cue whimpers of 'I didn't shoot the bird! I didn't!' for a few minutes. Later, after finding out what happened to the animals in the cages when Snake was captured... *shiver*
It gets worse after that. A giant inferno is blazing around the room above Naked Snake's head. Naked Snake barely makes it to the door as a giant flaming head of The Fury shrieks "FURRRY!!!" and then... KABOOM!!!
The worst thing you can hear the ghost of a dead guard say on the river; "You ate me! You ate me!"
The End's bulging eyeballs are both creepy and disgusting.
The Shagohod's explosive entrance into the world from the ruins of Groznyj Grad is nothing short of watching a dragon being unleashed into the world of Metal Gear. Rockets annoy it, and bullets are not even ignored, and nothing is able to stop it from tossing tanks aside like toys and mowing men down like so much grass with its thunderous charge. All this would not be so bad were it not for that nerve shredding Battle-cry, which is akin to the bending and distorting of metal meeting the screams of a giant baby.... Shiver...
The sequence in which Snake gets captured and is tortured by Volgin. In contrast to the torture sequences in the previous games, there is no fancy electrical equipment, nor is the player given the opportunity to heal themselves - Snake is simply left to hang from the ceiling while Volgin pummels him to a bloody pulp. It starts off incredibly brutal and shocking, and only gets worse from there.
It gets to the point where Big Boss pisses himself from the electrical surges going through his body, and Volgin is aroused by it.
The Pain interfering in Snake and Ocelot's fight, leading him to send a swarm after everyone in the area. Some of Ocelot's soldiers become cannon fodder, and their screams as they're stung to death leading their bodies to become horribly disfigured in the process is terrifying.
There are some points in the game when trying to contact EVA is impossible. Her inability to answer the codec is probably because she is busy being raped and tortured by Volgin while disguised as Tatiana
Metal Gear Solid 4
The various commercials that you watch in the beginning range from tame to disturbing, all featuring hints of Uncanny Valley. Probably the worst offender is the Bomb Shelter Buffet. It features cooks who work with animal carcasses on camera, including the chef cutting off the head of an alligator. It's Nausea Fuel all around.
The fight against Screaming Mantis. It doesn't help that the dead are reanimated, and you're dealing with a boss that can float and teleport in a game that isn't supposed to be absurdly supernatural. The second half of the battle is, if possible, freakier; dealing with a woman slowly walking up to you while effortlessly sidestepping your attacks as the screen goes to black and white, all while hearing a chorus of screams of what must be torture victims, made it a rather distracting battle. Oh yes, and she is begging, begging, for Snake to kill her. Sweet dreams.
The fight against Laughing Octopus. Octopus has a cloaking device that renders her near invisible, making night-vision pretty much your only option of seeing her. She can also go anywhere with her tentacles, meaning she could be right above you at any given moment. Also note the fact that she could disguise herself as a dead body, your pal the Mk. II, furniture, and your friend Naomi Hunter. It gets even scarier later in the fight when she does away with the tricks and starts to randomly jump out at you from the windows charging maniacally, allowing her high-damage dealing tentacles to hit you.
All of the B&B corps were freaky. Take beautiful women in what appears to be skintight latex, add horrible psychological problems and cybernetic augmentations, arm them heavily, have a scene that shows them slaughtering a dozen or so Faceless Goons and imply that they knew the Player Character was watching all along. Then in the second stage of each boss fight, you have to defeat the same women in their human form with their masks off, still in the bodysuits. If they get close enough, they can hug you to death. The repeated fetishistic shots of their feet don't help either, nor does the easter egg where you can take photos as they pose for you, in one case while one of the women is crying. Guess what the juxtapositions cause?
While most players find the Beauties' backstories full of Narm, Raging Raven and Crying Wolf have pretty realistically horrifying ones. Raven was abducted by insurgents as a child, beaten, starved, and had her flesh pecked at by hungry crows for who knows how long. Crying Wolf was escaping a war-torn African village with her infant brother, and accidentally smothered him to death while hiding from pursuers. Even worse, after that she began hallucinating and murdered every child in her refugee camp. After all of that, being put in a high-tech killing suit and forced to practically run on negative emotions sounds like the epitome of And I Must Scream.
Just a guess, going by these scenes and End of Evangelion do you think Hideo Kojima and Hideaki Anno know each other?
Never mind the constant screaming as the women stagger towards you, as the sounds of whatever trauma broke their minds play back.
Laughing Octopus is the creepiest. The others are fine. It's normal for someone in that kind of situation to scream, be angry, or even cry. Octopus just laughs the entire time. She's not even laughing at you. She's just...laughing. Even while you shoot her. And she just won't stop.
Zero's death in the ending: No matter how responsible he is for the countless atrocities and disasters caused directly or indirectly by The Patriots, watching a wheelchair-bound old man suffocate to death for several seconds as his air supply is cut off, right before he goes limp and flatlines, is not exactly pleasant.
The Gekko are extremely unsettling, on an intellectual level. Those legs aren't just nanotech synthetic muscles, they're actual cloned living ungulate tissue. They're basically two disembodied cow legs hooked up to life support, with a mini-tank on top. And after doing anything strenuous, they excrete excess lactic acid. Creepy. As. Hell.
They're very likely designed to scare and unsettle, especially considering the variety of bizarre noises they emit during combat. These range from the chirping of cicadas to the screams of cattle, the latter being particularly unsettling considering their relation to Japanese WWII air raid sirens.
Does the Uncanny Valley apply to legs? There's something very human- almost feminine about gekko legs but the color and size are off. The organic and inorganic nature of these things is also unsettling.
What Zero did to Big Boss: After supposedly being best friends and brothers in arms, Big Boss turned on Zero and left the Patriots. Zero's revenge? Have Snake "kill" Big Boss (in Metal Gear 2), retrieve his body, and keep it barely alive on life support, using him as the only working key to his super computer network that he chose to be his successor. And if that wasn't bad enough, it turns out that Big Boss is not simply in a coma - he's actually in a permanent state of locked-in syndrome, a state maintained by the nanomachines injected into his body by the Patriots. As a result, he cannot move, speak, or do anything, but he is fully aware of his environment. Okay, he can thrash about a little bit - which only makes it worse. And of course, it turns out they did this to Solidus too.
That bit where Snake wakes up with his pixelated MGS1 head on his hi-res MGS4 body. It just drives straight into the Uncanny Valley and never leaves.
The Microwave Hallway is a combination of this and Tear Jerker.
The Boss AI's speech dissolves into random phrases while its voice drops into static. Especially near the end where she just screams "Jack!" over and over in a slow, distorted voice. The Boss just should not sound like that. Ever.
The Peace Walker unit, specifically what would happen if it was mass produced, is also extremely terrifying to imagine. Aside from the fact that it can launch retalitory strikes at countries, or even be tricked into launching nukes at other countries by making it think that there was going to be an attack on the US homeland, there's also the fact that it is equipped with a huge hydrogen bomb so it could sneak into enemy territory and self destruct, most likely obliterating an entire nation. When you remember that Hot Coldman planned on mass-producing Peace Walker throughout Central America (from Belice all the way to Panama), it becomes a lot more horrifying when you take into account the implications of what might happen if he, or some other mass-murdering madman, decided to have all the Peace Walker units stationed in Central America self destruct in their respective countries. In fact, Hot Coldman is the most evil, insane, and depraved character in Metal Gear history, even outranking Colonel Volgin (If he managed to make even an extremely sadistic GRU Colonel who has absolutely no qualms about blowing up countrymen for laughs run for his money, you know that Coldman is bad news.)
Paz. Just...Paz. But to be specific, Paz the "peace-loving pacifist" really wants to unite the world under one will with Cipher and Major Zero. Paz wants to kill Big Boss despite struggling with Becoming the Mask according to her audio tapes, has very few problems launching nukes and framing MSF, was playing Big Boss for a chump since the start of the game, and hates kittens. "Say Peace!"
Metal Gear Solid V: The Phantom Pain
When Big Boss arrives to rescue Chico from Camp Omega, Chico freaks out and even lashes at him, forcing Snake to put the poor kid in a sleeper hold. Then the camera pans to nails driven through the heels of his feet to prevent him from trying to escape on his own.
Paz's brutal surgery. It's horrifiying hearing her screams and moans in agony, but worse hearing the fear in Snake's voice. Even worse? The surgery is done to remove a bomb in her stomach, which is the size of a freakin' postal package. Even worse, after CIPHER's destruction of Mother Base, she attempts to kill herself. Why? Because she has a second bomb inside her. In her vagina. Holy fucking SHIT, Kojima!
All of the things Big Boss goes through. He wakes up after a nine-year coma and is missing an arm, has to crawl his way out of the hospital, gets a piece of metal lodged in his head, and starts having all sorts of weird hallucinations.
Quiet being tortured in the "red band" trailer.
Skull Face. Just the appearance of Skull Face in general.
The appearance? Try what he actually does on for size - notably, his stripping and belting of Paz is extremely discomforting to listen to.
That pales in comparison to what he makes Chico do to Paz. Wanna know? He forces him to rape her
Big Boss apparently gunning down a group of imprisoned African slaves near the end of the trailer.
Metal Gear: Ghost Babel
While not a canon game, Ghost Babel never-the-less has one of the creepiest villains in the series, Marionette Owl. He was born with a condition that let him see in the dark and became a Serial Killer after finding his childhood friend cut to bits and strewn over a field by another serial killer. He was recruited into the Black Chamber unit after he was cornered by the FBI, but was given a pardon by the team's leader, Black Arts Viper in exchange for working for them. He fights against Snake in complete darkness while using two large marionettes. It's revealed that they aren't normal marionettes either. They were created using the severed limbs and body parts of his prior victims, and during the fight with Snake, comments that after he kills him, he's going to use his clavicle and femur bones to repair one of his marionettes.