Oh dear, I love too many horror games. However, being such a fan of them, I'm definitely submitting a vote right now, but I'm terrible at favorites. Going for the full 10 votes, but know that I could easily name more and more. I have a broad taste for the genre and part of me wants to name some timeless classics, while the other part wants to bring up some of my personal favorite more niche games I love, I'll try to do some mix here.
Keep in mind that these aren't in any specific order, I am just helping some titles I hold very dear personally, and I couldn't arrange them in personal preference order; I love them all.
REGULAR VOTES:
01.) WhiteDay: A Labyrinth Named School
An overlooked classic, though I do suspect it'll get some more attention in the next year or two as a pretty faithful remake (basically just prettier and with some new content, ghosts, locations, scenes, etc.), is releasing on PC and PS4 later this/next year. Already released internationally on mobiles... But anyways. WhiteDay was originally a 2001 PC Korean horrror game that was leagues ahead of its time. It is the first ever first-person hide'n'seek defenseless horror game with physics-based gameplay/puzzle game that would become popular 10 years later, and in mine and many other people's opinion, still one of the best. Game has a reputation for being one of the scariest games ever made (I think that's a bit overblown, buuut I will admit it's definitely higher up there for my personal 'scariest' games list, though the scares do somewhat scale to difficulty).
It has a very unique sound design, and funnily enough featured solutions to the hide'n'seek horror game that current games of the era that do this style have issues with, and solved them before they even existed. In WhiteDay, you are stalked primarily by a twisted janitor, who randomly wanders the school (he can literally enter any room at nearly any time), and you may hear him coming by the jingling of his keys. But the school is twisting; supernatural forces are at work here. And though hiding in the dark may aid you in hiding from the janitor, there are other entities inside the school who wander in the dark... Including a spirit who comes for you if you stay in one general location hiding for too long, slowly coming for you.
Has some fun twists and turns, some pretty good scares, split storyline with a few different pathways that make different scenes trigger depending what path you're on and multiple endings, and a number of hidden scenes, scares, etc. Excited for the English release of the PC remake!
Music Samples:
Byungki Hwang - The Labyrinth (segments of this song and variations of it are used a lot in WhiteDay)
One of the Credits Themes
02.) Hellnight (aka Dark Messiah)
Hellnight is another game from my potential scariest games I've ever played list. It's a unfortunately fairly unknown game by Konami & Atlus that they released in the late 90s on the PSX. Yes, Konami actually published another horror game outside of Silent Hill, and it turns out it's actually pretty good. Hellnight features you in first-person corridors, exploring an underground Tokyo subway/sewer system/military base that has been converted into an underground civilization for those who decide to fall out of modern society or have nowhere else to go. However, some strange robot suddenly attacks a train underground, with our main character who was riding it to go home, but gets caught up and chased by this monstrosity. He much team up with others to survive.
And that robot is the only enemy in the game, it is a persistent stalker who chases you the whole game; but there's a catch. It is evolving, becoming fiercer and more dangerous, and growing intelligence to trick you and play you into its hands. It changes shape and form, and grows trickier and more deadly as the game goes on. In the game, you have partner characters, you can take one with you through the game. Each has a special ability, but more so, each has a big presence in the story and you can grow attached to them... But if you do, you better play well. Get caught by the monster, and they die. Permanently. The monster catching you will perma-death your party member and completely change the course of the story upon their death. There's a few different partner characters, and having them die at your hands can be brutal. Get caught with no partner, and you're dead.
It has great atmosphere, a surprisingly complex and interesting story, some good scares and tricks. It's a bit slow-paced, but I feel it works to the game's benefit. You can go 20-40 minutes without running into the monster, for it to only appear when you least expect it. Outside of the monster, you transgress first-person 'dungeon labyrinths', and enter rooms into a point'n'click style where you may examine them, get/use items, talk with people, some puzzles, etc. I am quite fond of the game.
Music Samples:
Southwest Area
Little Jamaica
I didn't want to die like this...
03.) Silent Hill 3
This is my personal favorite of the SH series, but to be honest I'm tempted to vote for more of them. Honestly, I am super in love with Silent Hill 1, 2, 3, 4, Downpour, & Shattered Memories. I love all six of them for different reasons. Homecoming & Origins are okay, too. But in trying to fulfill a list full of favorites, I am trying to limit myself to a single entry per franchise (since I have so many other favorites out there), and if I had to choose my personal favorite SH game, I would vote for SH3 (though part of me wants to vote for something like SH4 & Downpour for how underrated they often are).
Silent Hill 3 is my favorite for a large number of reasons which may not be immediately evident to someone that plays it. I hear of many people who play SH2, and then go to SH3 expecting it to be like SH2, and then end up being disappointed... But I think more need to realize that SH3 is NOT SH2, it is it's own entry, and there are things it does so masterfully that just captivate me every time I've played this game. SH2 I do think has a better narrative and a certain cold atmosphere to it, a very down-toned and mature game, but I just overall like SH3 more, and it is one of the horror games I can replay over and over and never get tired of it.
There's a surprising level of detail to it, ranging from big differences in the game between difficulty levels, new game+, tons of secrets, tons of environmental details, subtlety everywhere... The game is gorgeous and has some of my absolute favorite environments in any horror game ever, in big part since every room is something special in SH3, full of details, interesting imagery, and I think the levels in SH3 have much better level design than any other entry in the series (I find their layouts much more fluid, fun to explore, and memorable, coupled with almost every room having something interesting to find in it). The characters are quirky and my personal favorite cast in the series, it has by far the best puzzles in my opinion (and this is heightened with how ingeniously inputted the puzzle difficulty option is), the best boss battles (and in extension, best combat the series had imo), best secrets... I could go on, but while I think there are elements the other SH game's do better (SH2 has the best story, SH1 I think has the best atmosphere, SH4 I think has the best scares, Downpour has the best overworld, etc.), SH3 sticks strong as my overall favorite. Had to include it in my 5 votes.
Music Samples:
End of Small Sanctuary
Letter - From The Lost Days
Memory of the Waters
04.) Resident Evil 4
An all-time classic. Like with the SH series, there's so many potential games I could name from the RE franchise to fit this spot. Hell, for myself personally, REmake is super close to being my favorite. But I have to give it to RE4, it is the game that got me into horror games as I am now (I used to be a huge scaredy-cat, this game helped change my mind to try and give them more of a chance, played REmake and other games after it). I think RE4 stands as my favorite for its excellent pacing, unique atmosphere, fun gunplay & monsters, enjoyably cheesy story, and just the sheer variety that there is in the game. As many will vouch for, this game is insanely replayable.
I can't really say much more that's not already been said by others, but I will say this; I think this game is as much of a horror game as the classic RE's. I love the RE franchise, but I think the scariness factor of the older RE's is a bit exaggerated (with the exception being REmake, in my opinion). They all have their moments, don't get me wrong, but I think RE4 was a natural evolution of what they were slowly setting up through the franchise, and I actually personally think it's just as scary as RE2/RE3, personally (there were a number of moments that got me the first time I played, ranging from Dr. Salvador, to the first Garrador, to the hedge maze, Regenerators, the invisible insects, 'IT', etc.).
It's known as one of the best games of all time for a reason.
Music Samples:
Save Theme
Echo in the Night
Wesker's Mercenaries Theme
05.) Fatal Frame 3: The Tormented
Maybe even more than the Silent Hill or Resident Evil franchises, I have such a hard time figuring out which of the Fatal Frame's are my favorite. Literally I like all four of the first Fatal Frame games about evenly (I still need to play the fifth game). I think FF1 feels like such a mysterious and yet engaging experience, but FF2 the best setting and ghosts, but FF4 I think has the best story and some of the most stand-out individual rooms...
But I'm giving the honor right now to FF3, which is maybe a bit of a controversial choice, but I'll try and explain my reasoning. FF3 is about a woman named Reiko, who's fiance dies in a car accident. She is grieving for a long period of time, and stays shut up in her house with her flatmate attending to everything, and begins to have mysterious dreams. Turns out, she may be under a curse that effects people in their sleep... A mansion only seen in dreams that causes a strange tattoo to form on the person's real-world body. The dream may ultimately consume them... But if they can reach the heart of the manor, they may meet someone precious to them who's passed away to spend one last moment together.
What follows is what is, in my opinion, the scariest FF game. It is a lot longer than the first two installments (it's like, a 15-22 hour long game), which features your house which you can explore in-between the mansion... But the things in your dreams slowly seep into reality... More hidden scenes and details than the other games, my personal favorite cast of characters in the franchise (and Rei is my favorite protagonist), as well as my favorite antagonist in the series (who also makes the best boss battle in the whole series. very well executed and creative). Match that with one of the spookiest locations in the series (in my opinion), some good switch-up gameplay (surprise) when you play as some other characters... There's more, but right now I'm leaning towards it as my personal favorite in the series, though it's an extremely close run for me.
Music Samples:
Reika
Kuze Family Head
Koe
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I'll keep the honorable mentions a bit shorter, but jeez, so many games, the above 5 I love to pieces, but they are tied with so many others already, but anyways...
HONORABLE MENTIONS:
01.) Penumbra: Black Plague
Really, maybe you should include all the Penumbra games together, since they were made to be episodic (all three episodes), and you can't even buy them apart anymore, only together as a 'complete' package. Well, if you include them separate, Overture is extremely close, but I ended up liking Black Plague the most due to its story, the fun personality of Clarence, the environments, encounters with the Greys, and some fun twists and turns. Penumbra stands as my favorite title from Frictional, though Amnesia & SOMA are also both very good.
02.) Ib
THIS WAS SUCH A HARD CHOICE FOR ME! There's so many RPG Maker Horror Games I adore to pieces, ranging from Witch's House, to Yume Nikki, to White Sky... But I decided to go with Ib, both as it was the first one I consciously played (I had played a few others like Ravenwood Horror and One Night before I knew what RPG Maker was though), but it is so universally enjoyable, started a big wave of actually pretty good games, introduced me to them properly, and is very creative. Little horror-puzzle game about a girl trapped in a museum where a certain artists works seem to be coming to life in a surreal way. Multiple pathways, endings, good story, characters, and puzzles.
03.) Haunting Ground
It's my personal favorite of the Clock Tower 'series', so I had to include it. Features actually one of my favorite settings in a horror game ever (Belli Castle is maybe one of the most underrated horror locations ever), some deranged and memorable stalkers, one of the best dogs in gaming, and a wonderfully twisted story that tackles several things horror games don't tackle often (including giallo and exploitation horror), it is a very fun ride through and through.
04.) Rule of Rose
Probably on my mind as I mentioned Haunting Ground (and though the two are very different, they have some outward similarities that has the two of them drawn together unconciously in my mind), Rule of Rose definitely deserves mention. Its gameplay has serious faults, but it makes up for it in one of the most unique and well-done stories in gaming, beautiful art and music, quite a unique atmosphere, tackling things almost no other game before or since dares to tackle with as much tact, maturity, and craft as done here. It is an experience and a unique rough gem.
05.) IMSCARED
There are SO MANY games I could name, SO MANY! But this one came to mind and I did want to end with one I don't expect many to name. IMSCARED is a 3D pixely metahorror game with some great tricks up its sleeve, a fun yet creepy antagonist, keeps you on edge and throws a lot of unexpected curveballs at me. Was a very fun experience for me, and one I include among my favorites.
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There is so many horror games I absolutely love, just as much as the ones I'm naming, that I feel disappointing only having to name 10, but submitting this as my vote, and interested to see what comes of this.