離開MTT渡假村後， 主角進入核心, Alphys便立刻緊張起來. 核心有大量敵人, 電梯沒法使用, 而在電梯的右邊的道路完全消失了. Alphys便指引主角去左邊, 並最終給了主角可憐的建議. 她最終因為尷尬而不和主角說話。. As the protagonist comes to the end of the Core, they meet Mettaton once more. He reveals to the protagonist that it was he who hired monsters to attack the player, as well as him that broke the elevator, removed the pathway, etc.
Mettaton explains that all of the encounters between him and the player, as well as all of the puzzles the player must complete were designed by Alphys as a way for her to insert herself into the player's story due to her admiration. Mettaton, however, got bored of this and by the start of the Core began to legitimately plot against the player, so as to cause incredible drama and excitment within his show. Likewise, him gaining the soul of the main character would allow him to prevent Asgore from killing humanity, and allow him to exit the barrier and become famous on the Surface- in front of 'hundreds of millions' of fans.
After the player defeats Mettaton, Alphys makes her way into the room, panics over the damage done to Mettaton, but reveals that it was only that his batteries ran out. Right before leaving for the city, Alphys reveals that Asgore cannot allow the player to leave, and for them to escape they will have to kill Asgore and harvest his soul to be strong enough to pass the barrier.
- 但是，有一天他掉进“自己制造的机器（可能是核心）”中，导致他的生命 "突然停止（cut short）" 。当普通游玩游戏时，没有怪物会提到Gaster 或是核心的起源.
|地表世界||伊波特山 ● 地下世界|
|廢墟||蜘蛛烘焙坊 ● 居所 ● Toriel的家 ● 廢墟走廊 ● 廢墟大門|
|雪町||雪鎮森林 ● 神秘的門 ● Grillby's ● 骷髏之家|
|瀑布||垃圾場 ● Undyne的家 ● 閃電蝸牛 ● Temmie村莊 ● 神器密室 ● Gaster的房間|
|熱地||實驗室 ● 藝術俱樂部 ● MTT渡假村 ● 核心 ● 真正的實驗室|
|新居||Asgore的家 ● 屏障|