I clicked on the link ... don't understand it, what's the deal?
Ok, SPOILERS from here on out, will use warnings in this post only:
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So it *looks* like a dating sim but what you realize is something is wrong with all the girls.
And then you realize that someone is *making* them that way.
MOAR SPOILERS
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Your supposedly ditzy cutesy friend Sayori actually suffers from crippling depression, the tough girl freshman (Natsuki) is abused by her father, and the weird girl (Yuri) cuts herself for sexual pleasure.
That leaves the last girl, Monika, and you realize eventually as you try to replay to save Sayori (who hanged herself in your first playthru no matter what you do) that she is self-aware. Realizing she was just a program drove her to tweak the personality of the other girls, as well as making their lives worse.
You the end up in a room, in a strange Void with Monika who you can talk to about random topics until you decided to go into the game files and delete her character file.
But this is, oddly enough, just the first part of the mystery that I'll get into next post.