This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Resident Evil 3: Nemesis
Resident Evil 3: Nemesis is trying to be scary, it's Survival Horror, but it does better than expected with the eponymous monster. The reason? Unlike most of the enemies, it can appear anywhere. The only clue that it's about to attack you? The music turns dramatic and a voice groans "STARS..." from just offscreen.
Not only that - sometimes he never makes an appearance in a particular area, there's no music, and you'll still hear that distinct "STARS...." off in the distance.
Nemesis's introduction sets the tone for the rest of the game when he kills Brad in front of Jill via a tentacle to the face.
A particularly scary music is the misleadingly titled "Never Give Up The Escape", heard mainly in empty rooms, of all places. A low drone piece punctuated by bell scare chords, and ominous ethereal choir.
Let's not forget "Feel the Tense" playing in the background when the Nemesis can still show up at any time.
The Clock Tower has this in spades once Jill has been infected. Making your way back from the Hospital as Carlos, Nemesis suddenly attacks in the main room with the stairwell, he doesn't follow you into the dining room, but then promptly proceeds to blaze in through the flames the room outside the save room. Then, when in control of Jill, he shatters the door leading into the dining room, throwing away all effects of subtlety. That entire sequence, unless you're trying to fight him for weapon drops, is an exercise in 'ohGodohGodohGodohGod'.
If you run away from Nemesis while you're playing as Carlos, he'll go after Jill in the chapel instead and it is possible for him to kill her.
In one cutscene, either Carlos or Nicolai is forced to kill a comrade named Murphy who is turning into a zombie.
It's arguably worse with Carlos; Nicholai's outright sociopathic and has no problem shooting the man, but Murphy has to beg Carlos to kill him.
Even worse: Murphy may not have actually been bitten in Nicholai's story. Remember, this is Nicholai we're dealing with after all.
A bit of Fridge Horror really, but you'll notice quite a lot of buildings boarded up rather well that you can't enter and there appears to be no sign the zombies broke into these homes. This implies there are still people holed up in their homes hoping for a rescue. If only they knew....
There's a slightly more solid hint for this Fridge Horror if you know where to look. If you revisit the street with the boutique and the bar where you meet Brad, you'll find two corpses lying in the street that weren't there before. Also, there's a fire escape that was originally accessible you could ascend to get some herbs. Once night falls, it's been drawn up and impossible to ascend. Someone must have pulled it up behind them, possibly even leaving those two for dead.
In RE2, one file found in the station mentions the loss of several cops, including an officer named David; here you find one that he left behind. He talks about how he ran as a fellow officer who saved his life was killed, screaming for help, and how hopeless and insane the situation is. He ends the letter mentioning how his old friend Mossberg is going to be "turning one more body into fertilizer".
The very idea of Nemesis - a Body Horror-infused Implacable Man with Combat Tentaclesand the brains to use heavy weaponry, whose sole drive overriding everything including pain and any instinct for self preservation is to hunt you down and kill you. Early in game, it's unlikely you'll have enough ammo to take him out. Ah well, there's always the ability to run; Tyrants are always slow in their first form. Except for this one. He can chase you down right from the get go. Add in the rocket launcher, the fact that he can chase you between rooms, and his instant death attack in his first form, and you've got nightmares.
And while some of his appearances are scripted, others aren't. The Nemesis can find you anywhere. The only place he can't show up is the Save Rooms, and if you were running from him, he'll be at the door when you're done...
The first time the player enters the chapel save room in the clocktower. After collecting one of the keys at the back of the room and making their way to the exit... the ceiling suddenly vibrates. Plaster rains down. The soothing save room music abruptly stops. Nothing else actually happens, but the fact this happens in a save room is horribly unsettling.
The aptly named "Dead Factory". The complex itself is nightmarish; it's a treatment facility used to clean up after Umbrella's mess and do away with the bodies, but in the events leading up to the game the factory became overflooded with bodies and failed test subjects that the treatment fluid became contaminated and the virus began to spread within the factory. The place is gravely unsettling when you visit it. The most chilling fact however is that there is a document found in the complex which details employees how to handle trespassers even if they accidently stumble upon the factory. Basically if they resist, they shoot the civilian and if they surrender they are taken captive and used as test subjects. What the hell?!
Some of the death animations (you can see all of them here, but be warned, it's not for the faint of heart) are pretty disturbing, like when the Nemesis picks up Jill and slams her to the floor over and over again, and when the Hunter-Gammas swallow Jill whole. The former is especially disturbing because of the overkill aspect.
The destruction of Raccoon City itself is incredibly eerie, especially with the creepy ethereal choir playing over the FMV showing the missile exploding. Not to mention that said scene was accurately depicting the effects of a nuclear bomb going off. Not to mention this game broke a pattern with the ones before it; where as RE 1 and RE 2 both fell into bittersweet territory, not even Jill, Carlos and Barry Burton whom comes to rescue them via helicopter can soften the blow of the horrifying scene of Raccoon city being leveled to rubble.