Unmarked spoilers below!
- Just about everything centered around the Cult of Ch'thon and the Void, From their rituals which involve bleeding people dry for their blood and from what you can see around their camps it tends to involve stringing people up and cutting them in various spots and disemboweling them, or just plain cutting a man in half. Then you have the creatures that these rituals bring forth, one such creature was summoned and proceeded to devour an entire village worth of people.
- The quest "The Origin of the Slith". The notes left behind by the scientist Oswald Hargate detail how he took his wife, Helen, and daughter, Ellena, to live on the island so he could further his Aether research. Hargate began experimenting with mutating swamp adders and eventually fusing them with local Grobles, but the hybrids created were malformed. While Helen and Ellena were away, Hargate paid mercenaries to capture travelers and bring them to the island, and then attempted to fuse them with the snakes. Helen returned and witnessed Hargate's horrifying experimentation, and she objected, leading Hargate to kill her. The hybridized travelers eventually died due to having an incomplete digestive system, so Hargate notes that he ought to try the experiment on a younger subject. That is where the notes end. The kicker? The level boss, fought in a cell in Hargate's basement, is Ellena, the First Slith - Hargate's hybridized daughter.
- The notes left by a mother who is trapped in the snowy mountains with dwindling food supplies. As the hunger drove them mad, they lost all sense of humanity and began killing and eating other survivors in their camp. Eventually, the surviving mother and her daughter don't even bother to cook the flesh anymore. As they become more bestial and feral, they start hunting other humans in the wild when all the people in the camp were eaten. The little girl is only nine years old. By the time the player stumbles upon the mother and her daughter, they've become mindless, ravenous Wendigos.
- The Aetherial occupied Malmouth takes the horrors of Port Valbury and cranks the dial up to eleven. The Aetherial Vanguard takes the Body Horror of Aether Corruption to new heights with their basic soldiers being hulking monstrosities with whip like tentacle growths, the exploding Scamps who are heavily implied to be the corpses of children, and groaning, bloating horrors that disgorge flesh worms when killed. And that's just the Aetherial front; the human element does an excellent job showing just how despairing and hopeless the situation is for Malmouth's survivors. Almost immediately upon entering the city, you come across a worn, haggard resistance on their last legs, a deranged Crazy Survivalist whose kidnapped two kids and may attack you no matter how calming and reasonable you try to be, and a devastated woman who is forced to leave her husband behind because he's too heavily wounded to be sent through your Rift.
- The last level of the expansion "Ashes of Malmouth" is this combined with the Nausea Fuel. It's like Crate Entertainment asked Hiromu Arakawa to decorate the place and she used Envy's skin for wallpaper. The sound of moaning in the background only make it more unsettling. And of course, it's conceptually horrifying as well, since it's essentially an enormous underground fortress made entirely of living human bodies melded together into construction material and "machinery" of sorts that the Shaper of Flesh felt was needed to keep his operations running. Including the giant womb (made with living women) for providing more bodies. Both Theodin Marcell and the Aetherial spirit possessing him were uniquely sick.
- After you kill monsters, their 3D models will slowly disappear. Sometimes, they'll be twitching while dissolving in nothingness, making the whole thing disturbing to watch.
- You can sometime find loot inside hidden walls. And some other times, it's not a chest you find, but a corpse, meaning that some people walled themselves willingly to escape the Grim Dawn. That, or they were Buried Alive by someone else prior to the invasion. Either way? Brr.
