Killer7/Nightmare Fuel

Killer7 has such fascinating boss encounters as a pair of Japanese businessmen who rise from the dead after having their heads blown open, and then attack by shooting their exposed brains at you. Also, the Heaven Smile's laughter.
The boss fight against Andrei Ulymedia in the CLOUDMAN scenario is one of the most frightening boss fights in all video gamedom: after turning into a heaven smile, he slowly chases you through a maze of ambulances, all of which are horribly vivid and unnatural colors, and he is trailed by a huge string of what can only be described as bloody tentacles sprouting from his back, that drag his disembodied brain (which is, suffice to say, his weak point) behind him. It doesn't help that he kills you in one hit, and thanks to the camera position you can't look around corners. Which means that there is a very good chance you will run straight into him.
- Here's some advice: use Con Smith, turn every corner you see, and pray you get behind him on the first try.
  - Here's some Nightmare Retardant, That's not his brain. It's his Afro...
The less said about Curtis Blackburn and his "hobbies", the better.
- The more said, the better. Curtis Blackburn is a pedophile with a fetish for anime loli (Ayame Blackburn!) and he harvests organs for the US government from little orphan girls he molests.
- Just harvests their organs? oh no, Mr. Troper, you forgot the most important part; He uses a giant car-wash abattoir hybrid, that rids the body of all organs, cleanses it and closes it up, then leaves just a shell of the dead body. After the boss fight in the room outside you can see naked little girl hollowed out dead bodies. In the end, in an ironic twist, Curtis is finished off by the machine, after it's done with him he is hung on a hook and his dead empty body tumbles slowly from side to side. This troper would've lost his lunch right then and there had the game not been cel-shaded.
Greg Nightmare at the end of SMILE. He's an obese dead man still hanging from the ceiling who makes horribly distorted grunts and you beat him by shooting him in his horribly swollen balls. And after that Black Heaven Smiles appear and kill your entire party except for Garcian while sinister organ music blares in the background.
Susie's stories. She's a remnant psyche who, before getting killed by the Smiths killed her own mother by jumping out of a window with her, landing in a trash compactor. Killed her boyfriend with a rifle because he broke her window accidentally with a pebble, hitting her in the face, and also admitted to castrating lots of men. This troper was guffawed by people in GameFAQs admitting they would take head from her. (she is represented as a disembodied head)
The simple fact that nothing makes sense. The player's total disorientation makes for a constant sense of unease as utterly insane and violent things keep happening around them with little to no explanation. If ever a video game has given a truly vivid look into the mind of a paranoid schizophrenic assassin, this is it.

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