Undertale alternate timeline that takes place in the Genocide Route (Undertale) where Sans (Undertale) takes matters into his own hands and murders the rest of the monsters to reach LV 20 in order to kill the human where he would then spiral into insanity and hallucinate upon murdering his brother, Papyrus (Undertale) where Papyrus would appear as a floating head.
Sans is referred to as "Murder."