Nightmare Fuel: Nitro+
Nitro+ is one of the Darkest Visual Novel companies in existence to this day. Their works would generate nightmares even without the help of Gen Urobuchi. However, with Urobutcher in the Driver Seat, their works gives Hideaki Anno, 07th Expansion, and Junji Ito a run of their money of this. Visual Novel while simplistic in comparison to the later ones, sums up the first impression of their works very well: DARK. The story follows the life of a young man who sees something he shouldn't have seen, is captured and brainwashed by a shadowy organization called Inferno and then is given the choice "join or die". He is trained as an assassin by a soft-spoken girl called Ein. Ein is Inferno's top assassin, code-named "Phantom" and controlled by the sinister Scythe Master, who also brainwashed the man. The man is given the name Zwei and begins his work at Inferno. page.
Science Adventures (Chaos;Head, Steins;Gate, Robotics;Notes)
- This is what you get if Nitro+ creates a Mystery fiction. All the New Gen murders in the game have mysterious elements, particularly the second, in which the dead man has an eight-month old fetus sewn into his stomach; given the age of the fetus, it had to have been removed from the mother's body before birth. It is eventually shown, in flashback, exactly who the mother is and how this happened.
- There is also Takumi's red delusions, as the green delusions are lighthearted, funny, and erotic, the red ones are the polar opposite, darker, tragic, and Nightmare Fuel.
- Water drip doesn't scary? Now read this link  and  and try to imagine the horror by yourself. For info, one people who are fine with other method is very terrifying about this. Oh and Ayase goes through this thanks to Norose.
- Time Travel seems awesome doesn't it? Not if someone else decides to try to hunt you down and that every action caused in that time period results in the Butterfly of Doom.
Nitro+ CHIRAL (Nitroplus Boys Love works)
- Togainu no Chi: Keisuke's route involves Akira getting raped with TWO screwdrivers and one Bad Ending has a CG of Keisuke ripping Akira's intestines out of him. Also YMMV but Arbitro's modification to his pets which include removing their eyeballs and windpipe. Not to mention completely breaking the victim's mind so that they act like dogs or worst. This becomes Fridge Horror in Arbitro's Bad End since Akira has been brainwashed into being one of his pets.
- Another one of the bad endings on Keisuke's route is where he doesn't take the screwdrivers out, leaving Akira to bleed to death. And you want to know how to make the other bad ending worse? Do you? "Akiraaa...I love you."
- On one of the Executioner endings, Kiriwar has his way with Akira, then cracks his skull open with Mitsuko while Akira is begging him not to.
- One of Shiki's bad endings; after drinking Nano's blood, he goes insane and kills Arbitro and the Executioners. He then tells a bewildered Akira that he has surpassed his weakness and that everything will come under his control. He scares Akira so much that he's practically sobbing. But wait! It gets better! In the ending, where Akira has become a nymphomatic slut who takes pleasure by sleeping around and telling Shiki so he'll kill them, it's heavily implied that he has been driven insane by Shiki's treatment.
- After entering Toshima, Akira comes across two guys having sex. One of them Is. Not. Moving.
- To add on the above, one of the rules of the Igura is that the winner not only takes the loser's tags but they can do whatever they want to the loser. And, as Keisuke points out, there aren't any females in Toshima...
- Lamento BEYONDTHEVOID: Shibiku. Enough said.
- Sweet Pool only had Urobuchi Gen as an advisor but is still chock full of Squick, Body Horror and Mind Screw. The basic premise has Youji, the main character as the host of the female form of a parasite that makes him give birth to slug-like lumps of meat from his butt. Like Saya no Uta, the endings are Bittersweet at best but Makoto's ending involves him going crazy and eating Youji and due to his insatiable desire starts eating his own arm as well.