The Soulsborne series has some incredibly effective areas, and I wish future iterations (most likely a sequel to Bloodborne) would emphasise that aspect even further. The whole series is just a masterclass of building atmosphere without interrupting gameplay in any fashion. Off the top of my head some examples are:
- Tower of Latria in Demon's Souls. Gently tingling bells have never sounded so terrifying. The descent to the bottom of the second stage is just a nightmare, as you're without warning thrust into a low-visibility swamp with no sense of direction, enemies straight out of a nightmare, and a lack of understanding for what you're even walking amidst.
- If one has played Blighttown already, Valley of Defilement is just a more annoying version of it... until you get to Astraea, and make the mistake of stepping into the swamp in the boss room. Bloody, deformed babies rise from the blood and tear you apart in literally seconds. Yyyyeeeccchhhhh.
- Tomb of the Giants in Dark Souls. The lack of explanation for any of it is what makes it. Yeah, it's Nito's light devouring domain of death, you'd expect to see skeletons, yet... why are there house sized coffins all over the place? Who or what were they made for? Who or what were the giant skeletons we fight? Most unnerving are the skeleton "dogs". They're clearly humanoid, but not quite human in the way they move. Were they human once? What degraded them to this position? And let's not even mention the literally endless horde of baby skeletons rising from the water to attack you, while above you see adult skeletons kneeling in prayer en masse. A cult worshipping a god of death sacrificing babies to him.
- The worms in the Duke's Archives, more specifically the ones that drop the Soothing and Bountiful Sunlight miracles. The whole game you've been conditioned to attack anything that doesn't make a "talk" prompt appear, and you charge into a room full of enemies. And in the corner there are two left. Only something's wrong, They don't attack you or move at all, just kind of shiver in place. When you get closer you can hear clearly human sobbing. When you hit them they just try to escape. And there's nothing you can do to help them, only put them out of their misery.
- Bloodborne has too many of these to count, but to name a few: The Research Hall in the Old Hunters DLC, the first hallway when you enter the cathedral in Upper Cathedral Ward (when the horror violins slowly fade in), the walls in the Hypogean Gaol after you've defeated Rom (straight up holocaust imagery), the shade of Queen Yharnam before the Mergo's Wet Nurse boss fight, the final fate of the prostitute you tell to go to Cathedral Ward, the solution of the little girl sideplot in the early game. I also love how the Lovecraftian themes are implemented even to the gameplay: the more insight you consume, the weirder the world around you gets, the more bizarre things you start to see, and your Frenzy resistance goes ever lower. A fantastically simple implementation of the themes of facing something beyond human understanding.