As a kid, any game that had what TV Tropes calls a "womb level"

Shoutout to the Bottom of the Well in Ocarina of Time.

Subnautica scared the shit out of me as an adult in my 30s lol

Oh and this fucking rugrats level

https://static.wikia.nocookie.net/rugrats/images/1/13/Let_there_be_light_level.jpg/revision/latest/thumbnail/width/360/height/450?cb=20150628222313

Back in '99 playing Ocarina of Time for the first time the ceiling hands in the Forest Temple scarred the shit out of me

I remember me and some other kids watching an older kid play through Resident Evil 2 at a friend's house in 1998 and being scared out of our minds

Only tangentially related to the question, but I always felt like Donkey Kong Country 3 had some sort of...mysterious, haunting vibe to it. Like something in the game world was just...off. I think maybe the music fed into that, but the atmosphere felt a little spooky, even in all the bright happy areas. Never scared me really, but the vibe and mood have stuck with me all these years.

Anyone else get that from the game?

Other than that, a lot of Silent Hill 2 scared me, but I can't remember any specific parts that jump out in particular. I just remember being scared of it and trying to not play it at night. Made it through the game a few times though growing up. Other people mentioned a few specific points in Ocarina of Time that I agreed with.

Last Half of Darkness. Found it on a shareware CD back in '94 or so. Pretty tame by today's standards, but they created a lot of atmosphere with a PC beeper, plain text descriptions and a 16 colour palette. 13 year old me hadn't ever seen a horror movie and wasn't used to the idea of jumpscares.

If you know, you know.

Oh and one more is abes oddysee or exodus i cant remember where there was a scene with abe with his eyes and mouth sewn closed and i cant find it but it freaked me the fuck out. Also the screen where you can make him fart didnt please me for some reason.

I used to fuck around with the game genie and the sega genesis. I think my console had a problem but sometimes when I'd boot up Aladdin it'd corrupt the splash sega screen and scare the pants of me. I didn't touch the console for days after that lmao.

Tomb Raider, the lost valley level scared me as a kid, not because of the allosaurus but because of the pitch black dark skybox with no stars. I thought lara was in hell or something as a kid and gave me the willies, silly, I know.

I can't think of any games but Large Marge in one of the Peewee movies haunted me for years

I had to get my brother to play the undercity section of KotOR, the rakghouls (space zombies) scared me too much. It doesn't help that the people living inside the dilapidated outcast village tell you that you'll get infected by a single bite and transform into a horrible monster if you go outside the walls. Not to mention the fact that several villagers are sick in quarantine, and will transform if you approach them without the cure that you get a while later.

And of course, the first time you approach the village gate you see a villager begging to be let back in as he's being chased by one of the creatures. You have to choose whether to let him in and fight the rakghouls or let him die (which the gate guard begs you to do, for the safety of the village). They don't look super intimidating in retrospect, but I literally wouldn't set one foot outside of the gates until my brother showed me that they don't actually infect your character with the disease (it's just a poison DoT in game)

the Aladdin SNES game scared the fuck out of me as a kid, Jafar's snake form made me cry

SNES Jurassic Park was also pretty spooky, the first person sections and the T Rex coming out of nowhere

I don't think I've had a game "scare" me in the same way Aliens did my young self into nightmares for months^[and made it one of my favorite movies of all time too], but I've definitely played some very tense games that definitely had me on edge.

• Doom - Probably my first "horror" game simply by it's premise. This was made worse because there was keyboard only controls back then and I was terrible at strafing. Everything from the music^[SNES Doom E1M5 lives in my head rent free], the sound effects of the monsters, managing ammo, and the increasingly deranged levels (both layout and theme) all were layered together that had me on the edge multiple times. If my mom saw it she definitely would have banned it!
• Dark Forces - While not a horror game specifically, it does have its moments especially from its Doom heritage. I hated the third level, the sewer level, because those garbage tentacle monsters would jump up and bite your face with little warning. When I say little warning, I mean you might see, in the dark, a little tentacle eye peep out in the distance. Combined with it's dark maze-like layout and it has no humans made for a very creepy experience. I mean just look at this nonsense!

• SNES Jurassic Park 1 - It's all fun and games in this top down shooter until you enter a facility and suddenly you are playing Doom with velociraptors.

• Half-Life 1 - Definitely my first actual horror game. I've also raved about it before. If Doom laid the building blocks for a horror FPS (survival, sounds and music, levels, vibes, etc) Half-Life built a masterpiece. It was also a first that didn't have separate levels so everything felt like an unbroken survival experience where you were just trying to get out of the facility. The purely environmental storytelling likewise added to the horror survival experience. I also want to shoutout Half-Life 2's Ravenholm for bringing this vibe back.
• Aliens Versus Predator '99 - Being an Aliens fan made this a natural for me. Probably the fastest and most lethal xenomorphs in the franchise^[on the flip side, it is so satisfying playing the xenomorph (multiplayer and campaign) even if a sneeze could kill me. I would charge in to die and people would be killed with my dead body's acid blood ] made for a terrifying marine campaign. It's also scary being the marine in multiplayer too, until I get the minigun...
• F.E.A.R. First Encounter Assault Recon - Not really a kid anymore, but this should be on the list. If the Matrix and the Ring made a video game, F.E.A.R. would be that game. A GOAT FPS horror experience with top notch matrix-time gun-fu gameplay, AI that was so good there's a GDC talk about it, and a proper horror story line and atmosphere that genuinely freaked me out several times. Holds up both graphically and story even today.

Honorable mentions:

• The Library from Halo, which is mentioned elsewhere in this thread. I also had a lot of trouble with that spot when I first played it to the point I remember just running through most of it! Having played it again recently it's clear a huge chunk of the scary was the thought the Flood was infinite, because I cleared out the whole corridor on the harder difficulty without much trouble.
• Zelda Link To The Past online rumors - I believed an online rumor that the temple background music was designed to make you confused, so during my first playthrough I turned the sound off during the temples.
• Half-Life 2 and the episodes - More of a Haunted than a Horror experience, there are several times in the games that dip into horror.
• System Shock 2 - Janky but excellent atmosphere! It's tough to recommend because you can really fuck yourself over with the wrong build and there isn't a good way to know. Since the original System Shock was remade I'm holding out SS2 will get one as well.

Metroid Fusion when the clone Samus was around. The first "cutscene" where you see it blast through a wall and then jumpscare you with a close up used to make me shit myself, damn

The original diablo, I was idk 5-6 and gained access to the family pc. I had managed to get up to the butcher and well iykyk

https://youtu.be/ICvV83ZkD_E

This big dumb piece of shit scared the ever living god straight outta my soul. AHHH FRESH MEAT still tingles the ahh I'm scared part of my brain

I watched when my big brother played Silent Hill one night, and the locker poltergeist gave me nightmares for a long time

https://www.youtube.com/watch?v=YGmyqeaL9V4

everquest & getting lost and dying used to give me such bad anxiety. I was afraid that I would never be able to find my corpse and get my stuff back (this was before generic corpse retrival was possible) One time my character fell off a boat in the middle of the ocean and I panicked and deleted my character.

Left 4 Dead.

Weirdly Black Ops 2 zombies didn't scare me. World at War probably would've though.

there was a ren & stimpy game on the snes with a level in stimpy's mouth or something (?), and if you touched any exposed nerve endings the ceiling/his top jaw would slam down and crush you, stressed young me right out

In Halo 1 the level 343 guilty spark was terrifying as a child because a scene basically from Aliens plays out and you're running into this new type of enemy that is fast and hard to kill, even your normal enemies are afraid of them, you're wandering around in this mazelike building where everything looks the same and all you run into are corpses and flood and one insane marine who kills himself in front of you, you're running out of ammo and medpacs, there's no obvious way out. You can only revert to last checkpoint or restart the level completely. I felt relieved to run into a covenant because it meant I was on the right track, only to kill them and get lost again. I had to play during the day with the lights on.

Also this game scared the hell out of me as a very young kid but I only really saw the intro cutscene, something about all the rust and dark setting frightened me.

Anything Zelda related really freaked me out. I could only handle the most tame of games. Majora's mask especially

Anything zombie related too. The flood in halo freaked me the hell out

The only game I remember being scared by was the ending of the first Harry Potter, I don't know why but fighting that professor with Voldemort on the back of his head always gave me the creeps. As a kid I was easily scared so I guess it's not that big of a stretch.

But one thing that never made sense is that some games made me physically ill, I still don't know why, it wasn't motion sickness or anything of that, I just felt extremely weird and uncomfortable while playing, the two I remember the most was a Shrek game and a NBA 2K game I think, I don't remember if both were on the 360, but just super weird experience.

EDIT: Actually just remembered another one I was scared by. I had a CD with a bunch of game demos and one of them I think was Time Commando. I think there was a tiger that tries to kill you at some point in that demo and I just shat my pants any time it appeared on screen, I literally could not do anything from that point forward because of how scared I was of that tiger.

Funnily enough I've never been scared by a game

Though I'll ask you, have you had a game scare you now that you're older?

Loving the Scooby doo call out - that was a great game and surprisingly difficult. For me it's anything with giant spiders- spyro the dragon during my youth and elder scrolls game later on. Too heebie for my jeebies