Several characters mention that they (or their lackies) have been following you and know what you're up too. Heather mentions someone has been following her as well.
There is a quest around halfway/later in the game about a snuff film involving a woman being terrorised and killed, as well as a short dungeon involving the studio where snuff films are made. The scene shown is short and not very detailed considering the graphics of the game.
An early game quest involves going to the home of a drug dealer and decorations throughout the game may imply drug use, but there is no direct drug use on screen.
Ghouls are humans who are addicted to Vampire blood. You meet several of them. You can also turn an NPC, named Heather into a Ghoul, by having her drink your blood.
One of the ways of obtaining of blood points is feeding on rats. If you play as a Nosferatu, it's your only way of nutrition besides buying blood packs.
There aren't any detailed depictions of bugs, but there are swarms of presumably flies that hover around corpses and certain areas of the game. They make buzzing noises.
There is mention of a character's father abusing them as a child, but it is not incredibly detailed. (However the way it is explained is in remarks, so it is described insensitively.) This dialogue isn't required, however, and can be skipped.
Statutory rape is mentioned early in the main story concerning a character's CSA experience, and an optional side quest has dialogue mentioning that a character is made to have sex with someone because they owe him money rather than by choice.
There is a vampire that must eat flesh to survive, and they are shown doing so. It could be argued that it isn't technically cannibalism since they are a vampire, but I think it's at least close enough to warrant mentioning.
There are plenty of opportunities for the player to be killed by fire or sunlight, usually bursting into flames when doing so. There is also implication that all the NPCs in a certain area--that have not been killed by the player yet--will die in a fire.
Nosferatu can be considered body horror due to their twisted forms, but there are also certain vampires with body modifications that are intense enough to be body horror. There are also monsters implied to have been humans once that either have gaping wounds or general body horror.
One bossfight is against a mad doctor named Gimble who is all about amputations and prostetics. He attacks you with a severed arm. After the fight you can pick it up and use it as a weapon yourself.
An NPC metioned the mad doctor cutting of their finger.
A NPC named Lily is being used as a blood doll by Vandal in the Hospital. You find her tied to a chair when you come to free her. At the Leopold Sociaity you find an NPC named Ash in a cage, with clear signs of branding on his face. He also mentioned being tortured.
There are several corpses that can be seen mutilated, including eviscerated. There are also mutated monsters including one with a large opening in the stomach.
A quest in the main story centres around a hotel in which the father in a family murders the children and his wife. This is told through newspaper clippings and diary entries.
Several NPCs are getting kidnapped during the duration of the game. Most of them happen off screen (And you only get involved once you go out to save them) with the exception of Kiki in Chinatown. You will actually see her getting carried away.
Few jumpscares are present in the Ocean House Hotel, which is the creepiest location of the game. Also, some enemy attacks can be startling. But the game is not horror and doesn't revolve about scares.
In a side quest, a vampire tells the player they need to consume flesh rather than just blood to survive. This is not depicted on screen, but is overtly implied that they had eaten three people. Four, if the player makes a certain choice.
There is a required dungeon that takes place in the mansion of a vampire that has turned it into an "asylum" [sic] to watch "the insane" and such. The depictions of the patients in this mansion are outdated, but meant to be neutral. (Although they are enemies.)
Early in-game, Two characters are shown to have very heavily implied dissociative identity disorder or OSDD. It's not the best representation, but normal for 2004. Malkavians as a clan are predisposed to being mentally ill or are already mentally ill when embraced, and being a malkavian intensifies it. Otherwise, plenty of characters are implied to experience some kind of mental illness, but it's never stated outright.
There is a character with DID who makes threats with a gun, and one version of the protagonist is part of an infamously mentally ill vampire clan. Combat is essential to this game and you can make threats of violence regularly, so the Malkavian protagonist counts.
Not in those words, but it is very much hinted that Ash Rivers doesn't care about being dead or alive. He mentions going outside of his club to get killed the first time you meet him.
Yes, if you complete the quest for Imalia a character will be mentioned to commit suicide. Certain disciplines can cause enemies to strangle themselves.
Sometimes, sound effects (such as gun shots, screams, or bangs) are loud (to scare the player) or because the game is generally janky, so the audio levels are inconsistent at times.
In an optional side quest, the player is tasked with proving that a celebrity is not as great as she seems. After the side quest is completed, the player returns to the quest giver and will find out (through a newspaper) that the celebrity was filmed having some sort of intercourse with a llama. It's not detailed at all.
The player character can have s*x with some characters, but it's not shown onscreen. In Chinatown you can see a woman giving oral s*x to a man. Most of the female characters, player and NPC, are sexualized. There are prostitutes (though you can't have s*x with them) and strip dancers. At one point of the game you have to read a diary of a prostitute and may learn about sadomasochist tendencies of one of the characters. In one of the optional sidequests one of the minor NPC turns out to be engaged in an act of b********y though it only gets known from the news. There is an organization which tries to bring the end of the world by transmitting an infection through sexual intercourses.