In this take, Sans does not trust you at all due to the events that caused papyrus to die in snowdin. and in turn never actually believes in you, he gives you a second chance i phase 1, but thats it. after that its no mercy. phase 2 is similar to the sans fight phase 2 where it just continues the fight with no big opening and phase 3 has no fake papyrus and alphys. its just a one on one with sans, and after sans takes a fatal blow in phase 3, its over. no phase 4.

The intro will be different (because papyrus doesn’t remember all the timelines perfectly) because this take takes place after an aborted genocide and a neutral route, papyrus gets a sense of dejavu from your emotionless actions and decides to stalk the player, eventually leading to him intervening during the sans encounter by blocking your attack with bones, leading to him fighting and dying in snowdin and sans losing all trust in you.

Phase 1 is like disbelief but sans does want to hurt you. you killed everyone he knew after all. it would basically play out similar to the sans fight, minus the universe stuff, sans judging you for your actions and all, however he wouldn’t start believing in you fully at the end of phase one, instead giving you one last chance to go back leading into phase 1.5

phase 1.5 is basically your only spare chance, sans is still on guard but he’s giving you a chance to prove to him if you can be let go or if he should start being 100% serious against you, you can heal here and continue the fight or spare him.

phase 2 is phase 1 but more difficult because sans is taking this seriously now that he 100% knows you don’t deserve a second chance, like the classic sans fight, its moreso a continuation of phase 1, but harder, however it does bring in a new mechanic: phantom attacks. phantom attacks being fake attacks that are transparent and dont hurt you and the bone weapon actually being used to attack the player. still no blasters.

Phase 3 is basically a one on one with sans, he uses everything hes got to attack you with all out attacks that are long and daunting, and also uses blasters this time and the yellow soul mode.

Phase 3.5 is a short attack that is an attempt to kill you before sans dies