Pasttale is an AU which set after a neutral run, for the remade one, genocide. This AU was made by Bone Apetit, she scrapped it because she thinks it's "Old and Cringy". It's currently being remade even Bone thinks its Cringy, but she wants to make the story properly.
Old Concept ( Yes there is an Old one. But it's so cringy... )
Sans is living in a snowy snowdin, while wearing his brother's scarf, and wearing his hoodie. He roams around Snowdin for unknown reasons, there is still some survivors: Alphys, Asgore, Flowey, and Undyne. They are all currently are finding Sans, but Sans always try to stay away from them, and when they do find him, he would murder them. The reason why he would do this is because "it's bringing back bad memories."
Unfortunately, the idea was scrapped.
Sans do the sparing method, and Frisk spared back. Because of that, Sans killed Frisk, but Frisk didn't come back. Sans was full of relief, but he realized he cant reset. The only survivors is him and Flowey. They decided to get along, and try to get out of this place. A few days later, they can now travel to other AUs. Sans don't want to come back to his AU because he thinks it "Bring back bad memories" the same reason to the old concept.