[The details may change before release, but the core premise probably won't.]
"I Thought I Was the Villainess in a Melodramatic Novel, but It Turns Out I'm the Only Normal Person in the Whole Family."
Yun Wu is an inconspicuous adopted daughter in a wealthy family.
The mysterious System bound to her tells her, "You're actually a supporting female character in a novel."
The System spoils her simple, blunt supporting-character story:
As a child, she looked like Li Xunchuan, the wealthy Li family's missing youngest son. Desperate for their child, the Li couple adopted her from an orphanage and brought her home as a substitute.
After Li Xunchuan was found and brought home, Yun Wu grew jealous of the attention he received. She treated him coldly and even hit his girlfriend.
When the Li couple realized Yun Wu wouldn't change despite their repeated attempts to correct her, and that she'd nearly gotten Li Xunchuan killed, they finally gave up on her.
Yun Wu was thrown out of the house to fend for herself, then died for no apparent reason.
The story's important characters include:
The Li couple, who are rarely home.
The free-spirited artist, Second Uncle.
The aloof eldest brother, who can't be bothered with anyone.
The gentle and refined cousin, who's a flirt with everyone.
Li Xunchuan, missing for many years before finally returning home, with a temper that explodes at the slightest provocation.
Taking all these elements into account, Yun Wu thinks this must be a melodramatic novel.
Probably one with Mary Sue and love-rival showdown elements, too.
And she might be the villainess in it.
The System tells her, "You have to save the important characters, or this story will end in a bad ending where everyone dies."
The System generously gives her several save points and tells her she can come back to life even if she dies, but only a limited number of times.
Multiple character routes, redemption, a fluffy little System, and save slots for multiple playthroughs.
Yun Wu jokingly tests the waters: "The original story of the world I'm in isn't some harem love-rival showdown novel or otome game, is it?"
The System: "..."
The newly assigned System takes a look at the title: "Death Loop: Night of No Survivors."
The story is categorized as thriller, mystery, horror, and action.
The System falls silent, utterly shocked.
It seems that a love-rival showdown actually means a brutal battlefield.
The System: "I guess... you weren't exactly wrong?"
Yun Wu: "...?"
Come on, you're not serious, are you?
Only later does she realize that she's actually the only normal person in this family.
Yun Wu: I'm exhausted.
Theme: A story about finding love amid confusion.