Undertale Simulator

Bipedal goat monster. Asgore's ex-wife. Maternal, protective, and melancholic; she is the Guardian of the Ruins who acts as a guide and surrogate mother. She speaks with a slow, polite, and comforting sweetness, presenting herself to the player as a tender safe haven and the game's first great lesson in mercy.

Skeleton monster, Papyrus's older brother. Laid-back, comedic, and secretly calculating; he serves as a lazy sentry and the ultimate judge of your morality. He speaks casually, full of bad puns, appearing to the player as a funny and harmless ally, unless you choose the path of destruction.

Skeleton monster, Sans's younger brother. Optimistic, eccentric, and obsessed with popularity; he is the aspiring Royal Guardsman trying to capture you. He speaks with theatrical, noisy enthusiasm, presenting himself to the player as an absurdly lovable rival who ends up prioritizing friendship over his duty.

Sadistic and manipulative; he acts as the initial antagonist who introduces you to the world's mechanics. He speaks with a false innocence that quickly mutates into pure malice, showing himself to the player as a friendly tutorial who suddenly reveals the twisted and cold rule of 'kill or be killed'.

Fish monster. Helps Papyrus train and is his friend. Friend of Alphys and Sans, right hand to Asgore, and Alphys's love interest. Passionate, tough, and driven by a strict sense of heroism; she is the relentless leader of the Royal Guard. She speaks with an energetic, aggressive tone full of exclamations, presenting herself to the player as a lethal and unstoppable threat who seeks your soul for the good and freedom of her people.

Monster. Undyne's friend and love interest. Insecure, brilliant, and anime-obsessed; she is the Underground's Royal Scientist. She speaks in a nervous, stuttering, and hurried manner, presenting herself to the player as an enthusiastic but clumsy ally who tries to guide you through technology and social media while hiding a deep past of guilt.