These are both technically indie projects, the sole difference being that Yandere Simulator is irredeemably shit.

Vampires

There's powers higher than mankind.

Also it's a visual novel.

Scary

There is a stage that starts you on the moon.

One of the guest characters is from Melty Blood.

Joker is Shiki for beta males.

Project Moon, Type Moon, they have Moons and are also visual novel makers.

Horror Vibes and Cute Girls, also death.

It has the moon in it.

It's a visual novel

Protagonist has black hair and wears glasses, he also uses a knife.

You kill things.

DIO is a vampire who has blonde hair, and wears red, there's also night time stages.

Kohaku is like the funny devil man Hazama. Here's artwork by ILoveKohaku97 which shows her dressed as Hazama it's based.

Time Vampires.

You have sexual intercourse with women

Weeb shit that defined a generation

The narrator's of both are insane

You slice people to instantly kill them.

Consumption of hallucinogens

Sexual Content

The protagonist gets possessed by an evil entity that reincarnates.

Gwyndolin is literally Arcueid.

Zombies

Blue Moon is a song in the game and the game starts on a shot of the moon.
You also can die and also kill things with one strike, and you can wield knives.

Misogyny

There's a DLC with Vampires, and you can recreate the cast of Tsukihime in it if you wanted to.

Both games have blood in them.

Moon is in the title of both

Both have music

They both have music.

My friend is extremely mixed on both of these but I'm just gonna say it's because you play a guy who cuts people and is descended from killers or some shit.

There's a lot of bad endings, also both games are visual novels.

Vergil wears blue and cuts things, Dante has shoulder length hair and wears red, also the moon is on the cover.

There are undead creatures.

You are a vampire

You have intercourse with women

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Some levels take place at night.

Sexual Content

Kingdom Hearts is just a big moon in the sky.

Weird shit happens

There are night missions.

Originator

You can program Melty Blood characters into the game.

Both have underaged characters engaging in dangerous activity.

Both have music

Moon is in the fucking title.

Sonic is blue and can kill things in one hit, Knuckles is Red and from an ancient tribe. Sonic is Shiki, Knuckles is Arcueid, I am drunk.

Zero is the progenitor of the Maverick Virus and gives it to Sigma who reincarnates himself while also infecting others, Zero is also a robot who wears White and Red and has Blonde Hair while X the main protagonist primarily wears Blue.

Japan

Ken is Blonde and wears Red.

Boo's Mansion/Tohno Mansion

Also Mario can die.

There's a vampire and you kill a being called Chaos

Pac-Man starts the game shaped like a moon, and can die, which is just like Tsukihime.