Splatterhouse/Nightmare Fuel

The arcade/PC Engine/Genesis series Splatterhouse, which was survival horror before there WAS survival horror, not to mention one of the most Body Horror filled games you will ever see.

"Terror Mask: Wait, wait, wait - I know this guy! Yeah, we are screwed."
 * JENNIFER HAS BECOME A MINDLESS BEAST.
 * The first level has you lopping the heads off flayed ghouls, while you stride calmly past partially vivisected people in cages and strewn on the floor.
 * The first boss is a room full of shredded human flesh from which giant leeches leap out and try to attach themselves to you.
 * Your girlfriend who you are supposed to rescue instead mutating into a hideous clawed monstrosity you have to kill.
 * The final boss being a giant rotting head and hands.
 * Said boss can be Nightmare Retardant if you remember the fan nickname (Captain Mozzarella), or note some weird details about it (for example, why his head pops out of the ground but his arms comes from below the screen).
 * The final boss of the second game topping that by being a giant flying mass of red flesh and screaming faces.
 * The third and final game's second boss. His laughter haunts me to this day.
 * You know you have a winner when the monsters that appear on the boxes' title art are significantly less scary then what you encounter in-game.
 * You forgot the Womb Level in the first game where the only enemies are horrid fetuses that first fly off in a sort of bubble, then jump on you and drain your life away. And the boss is a pillar of meat with the bulging heart of the house that sends off millions of these "babies". (This troper loves the game for all the horror in it.)
 * The heart is actually a uterus. It's more apparent in the arcade version, where its water breaks when it's destroyed.
 * All of the bad endings totally scare the hell out of me. Hell, even the good ending does!
 * The arcade game employed some trick with its sound to make the effects of the carnage seem to be beamed directly into your inner ear. It cost 25 cents to play, plus $500 in therapy bills.
 * The third game is made all the scarier with pictures of the characters that are low-res, yet photorealistic. Didn't save Jennifer in time? Good luck sleeping tonight, motherfucker!
 * Ladies and gentlemen...Biggy Man, from the Splatterhouse remake! And yes, you fight him the classic way AND the 3D beatdown way. The first time you see him is when the room is pitch dark and sparks suddenly shoot out. Then when you actually get to his fight, he RIPS OFF THE ELEVATOR DOOR to start it.
 * Then comes the 3D fight itself. It starts off in 2D, doing it the way it was back in the first game. Then it goes into a 3D perspective, which makes this guy 10x worse! When you try to do the usual Splatterkill to finish him off...HE ESCAPES FROM YOU and then makes you look around an entirely pitch black room with just the revving of his chainsaws dragging across the ground as he rushes toward you at the last second! Have a good sleepless night.
 * The worst part for this troper was actually the cut scene right after the fight, where Rick repeatedly rams one of Biggy Man's chainsaw hands into him, all the while you can hear him screaming in agony. From what I can tell, he's the only monster in the game to actually SCREAM in agony. The screaming... dear God the screaming...
 * The Doll that Bled. If the title of the level wasn't eerie enough, the titular Doll is really going to bother you. First you see a creepy looking doll, which the Mask seems a little cautious about it. It then begins levitating all the furniture around thr oom, in obvious reference to the second boss in the first game. Then, the Doll starts growing tentacles. Lots of tentacles. It then proceeds to grow into a mammoth, vaguely humanoid beast composed entirely of tentacles, wearing the levitated furniture as body armour. From then on, it's okay...until you actually have to rip its jaws off and reach into its bloody mass to reach the Doll.
 * The doll itself is very creepy, falling easily in the Uncanny Valley and says "Mama!" with a chilling, disturbing voice.
 * The Meat Factory. Imagine a factory dedicated entirely to killing. There is no reason for it to be, it is merely an entire complex designed to, well, make 'meat'. There are even a few walls that are actually composed of mangled human flesh. And did I mention that this where you fight Biggy Man?
 * One level has you enter a house of mirrors. Each room had three, each with the reflection of Jennifer. The first reflection begs you to save her. The second emplores you to run and save yourself. The third tells you how pathetic you are. You need to break one of the mirrors to get to the next room. If you choose the wrong one, an evil Jen clone will burst out and try to kill you. And if you run out of time, a small army of Jen clones appear. God help you if you don't have Berserker Mode available.
 * One of the bosses is inside an abandoned church. Said monster is an upside-down cross with demonic masks firing at you.
 * It may double as a Funny Moment to some, but... back to Biggy Man... not just his appearance and way he fights, but also the Terror Mask's words upon seeing him in the remake. The TERROR MASK is worried about fighting him, even though Rick is quite plainly pointing a shotgun in his face!!


 * Crossing over into Tear Jerker, we have the moment in the first game when Jennifer is turned into a monster. There are horrifying implications before and during the ensuing boss fight. First of all, you saw the monsters surrounding Jennifer just before she transforms, which may have just been the end of whatever arcane ritual was required to transform her. Or it may have been something else. Then as you fight her, she seems to painfully switch back and forth between her human and monster forms.
 * The gigantic Cthulhu-like monster in the tank near the end of part 6. Said beastie will growl at you and try to reach Rick by hitting the walls of the Tank.
 * OH GOD, this thing. What really makes it creepy is its status as a Big Lipped Alligator Moment, as there is absolutely zero findable knowledge on what it is and what its doing down there, and West himself says nothing about it when Rick finds him for the stage's boss fight. Scariest thing in the entire franchise, indeed. o.o
 * The Clown Corrupted. Just the freaky, fire-spitting Clown Corrupted.