Complete Timeline of Toby Fox's "Undertale"

Introduction

• Presenter: Mario Bueno, The Leaderboard
• Focus: True pacifist timeline of Undertale
• Spoiler alert: Full game details
• Canon only: No theories, strictly canon events

Pre-War Peace

• Humans and monsters co-exist peacefully
• Humans grow wary of monsters' potential power
• War breaks out between humans and monsters
• Humans win and seal monsters in the Underground using a magic spell
• Barriers around Mount Ebott are formed

Life and Death of Asriel

• Rulers: Asgore and Toriel Dreemur
• Son: Asriel Dreemur
• Asriel finds an injured human child, Chara
• Asgore and Toriel adopt Chara
• Royal scientist Dr. W.D. Gaster creates the CORE and disappears
• Chara’s Goal: Vengeance on humans, plan to harvest a monster soul
• Incident: Chara poisons themself; Asriel absorbs Chara's soul
• Outcome: Asriel and Chara travel to the surface
  • Confronted by humans, Asriel mortally wounded
  • Asriel returns and dies in the Underground; his body turns to dust
• Aftermath: Asgore declares war on humans; Toriel leaves and buries Chara
• Six humans fall into the Underground and die over the years; Asgore collects their souls

Determination Experiments

• New Scientist: Alphys replaces Dr. Gaster
• Task: Find a way to break the barrier
• DT Extraction Machine: Extract determination from human souls
• Experiments: Inject determination into dying monsters; creates Amalgamates
  • Flower Experiment: Inject determination into golden flower (Asriel reborn as Flowey)
• Flowey’s Abilities: Learn to save, load, and reset timelines
• Flowey’s Actions: Numerous resets; begins killing monsters out of boredom
• Sans’ Response: Attempts to stop Flowey, resulting in repeated resets

Important Events

• Characters: Sans befriends Toriel, Undyne becomes head of Royal Guard, Alphys and Undyne meet
  • Papyrus aims to join the Royal Guard
• Undyne & Alphys: Meet at the Garbage Dump; develop feelings
• Spider Bake Sale: Organized by Muffet

Main Events of the Game

• Frisk: Player character falls into the Underground
• Initial Encounter: Flowey tries to kill Frisk, rescued by Toriel

Ruins

• Guidance: Toriel teaches Frisk puzzles
• Napstablook: Encounter and cheer up sad ghost
• Toriel’s Home: Toriel offers to let Frisk stay; Frisk insists on leaving
• Boss Fight: Toriel vs. Frisk (spared in pacifist timeline)
• Flowey's Warning: Frisk can’t maintain peace

Snowdin

• Sans and Papyrus: Meet and interact
• Monsters Encountered: Snowdrake, Ice Cap, Lesser Dog, Jerry, Doggo
• Nice Cream: Meet Nice Cream Guy
• Papyrus Puzzle & Fight: Papyrus' traps, ends with friendship, and phone number exchange

Waterfall

• Grillby's with Sans: Optional
• Undyne’s Pursuit: Several confrontations, ends in the Hotlands
• Monster Kid: Follows Frisk
• Napstablook’s House: Calm moment
• Mad Dummy Battle: At Trash Zone
• Undyne’s Heatstroke: Helped by water, leads to meet-up and cooking lesson

Hotlands

• Alphys: First meeting; helps Frisk in various Mettaton TV shows
• Mettaton EX Battle: Reveals his desire to stay, ends with fans' love
• Monster Soul Revelation: Frisk needs Asgore’s soul to leave

Capitol

• Requirement: Must have at least one neutral ending before true pacifist ending
• Asgore Encounter: Initially fight; spare him
• Flowey’s Suggestion: Befriend Alphys, deliver Undyne’s love letter
• True Lab: Encounter Amalgamates, learn about determination experiments and Chara’s history

The Final Battle and Ending

• Monsters United: Monsters try to protect Frisk
• Flowey’s True Form: Reveals as Asriel Dreemurr
• Battle Asriel: God of Hyperdeath form
  • Save friends’ souls, including Asriel’s
  • Asriel apologizes, releases souls, destroys barrier
• Ending: Frisk returns to the surface with friends
  • Asked to be human ambassador for monsters
  • Option to stay with Toriel or explore independently

Conclusion

• New Era: Monsters and humans can live together in peace
• Potential for more: Exploration of genocide timeline
• Sign-Off: Mario Bueno, The Leaderboard