New Home is an entirely gray setting, occupied by long corridors and what appears to be a large city in the background. It does, however, contain the Throne Room and the Last Corridor, both of which are well-lit, brightly colored rooms, primarily sunlight-yellow. Onionsan mentions that there is a large aquarium in New Home and that it is overcrowded, but this is never seen.
After Mettaton EX is defeated and Alphys warns the protagonist that Asgore must die for them to be able to pass the barrier, the protagonist enters New Home. A series of encounters occur, starting in Asgore's Home. These encounters are non-combative (as the monsters do not attack the human), but instead, they detail the well-believed history of Asriel and the first fallen child, about Asgore and Toriel.
It is explained that after the first human had fallen into the Underground, they were found by Asriel and treated as a second child by Asgore and Toriel, but eventually became lethally sick. The human's only wish was to see the Golden Flowers of their hometown. This, however, could not be fulfilled as the monsters were not strong enough to pass the Barrier without a human SOUL. The human died, and in grief, Asriel absorbed their SOUL, passed the barrier, and returned the body of the child to the town.
Believing that Asriel was the cause of the human's death, the townspeople attacked him, and sustaining numerous injuries, he returned with the fallen child's body and consequently perished in the Underground. Heartbroken after losing two children, Asgore declared that all humans that fell into the Underground must be killed and have their SOULs collected, so as to be able to destroy the barrier after attaining Seven Human SOULs. Toriel was disgusted by this, and relinquished her title of Queen and left Asgore to live in the Ruins and protect all humans that fell there.
After this explanation, the protagonist makes it to the Last Corridor, where Sans appears and reveals the meaning of EXP and LOVE. Additionally, he judges the protagonist based on their degree of EXP and LOVE. Depending on how many/what monsters the protagonist has killed, Sans's reaction ranges from hesitantly proud to bitter (especially if they killed his brother, Papyrus). After this, the protagonist confronts Asgore in the throne room (A short detour shows a set of seven coffins, of which the closest is titled the name given to the Fallen Human). He is polite, friendly and extremely hesitant during the entire encounter. He goes to wait for the protagonist at the barrier and lets them decide if they have anything to do before their destined battle. Once the protagonist has done everything, they will fight Asgore.
After defeating Asgore, the protagonist is unable to go back and must make their way to the exit.
True Pacifist Route
In the Last Corridor, Sans praises the protagonist for not gaining any LOVE. He tells them that they will soon face their greatest challenge, but that he has confidence in them because of their determination to do the right thing.
After exploring the True Lab, the protagonist will receive a strange phone call and will then be forced into New Home, with the elevator to the CORE jammed shut by vines. All SAVE Points except the last do not appear, and no monsters (including Sans) are present until the Asgore fight.
When the protagonist confronts Asgore, their friends appear and intervene to stop the fight.
The protagonist encounters Flowey multiple times, starting at Asgore's Home until the Last Corridor. Functionally, this is a replacement for the story of Asriel and the human's death given on pacifist and neutral playthroughs, featuring Flowey detailing his thoughts and feelings about his life after being resurrected as a flower with determination, limited positive emotions, and no empathy.
In the Last Corridor, Sans will judge the protagonist on their past actions and murders and commence the final boss fight of the Genocide Route. Entering the throne room afterward revokes input actions as the ending commences.
- In the Genocide Route, the keys are put on the cell phone's keychain, despite the fact that Alphys does not upgrade the protagonist's cell phone with a keychain on this route. This may be an oversight, or indicate that the keychain was an original feature of the phone only mentioned by Alphys in passing.
- ↑ "He-hey! That's OK! It beats moving to the city! And living in a crowded aquarium! Like all my friends did! And the aquarium's full, a-anyway, so, even if I wanted to, I..." - Onionsan