Undertale has three different endings: Neutral, True Pacifist, and Genocide.
- For more detailed explanations of this route, see Neutral Route.
A neutral ending occurs under any of these conditions:
- If the protagonist does not befriend all plot pivotal characters (Papyrus, Undyne, Alphys)
- If the protagonist kills any monster.
The Neutral Route ends with the protagonist escaping the Underground alone. There are a variety of different possible variations of this ending depending on the choices made throughout the game.
True Pacifist Route
- For a more detailed explanation of this route, see True Pacifist Route.
This ending occurs when the following criteria are met:
- A Neutral Route has been completed.
- No enemies were killed throughout the game. (The protagonist cannot gain any EXP, and as a result, they cannot progress past LV 1.)
- Papyrus, Undyne, and Alphys have been befriended.
- A Genocide Route has NOT been completed before. Doing a Pacifist run after a Genocide route will result in an altered "Soulless Pacifist" ending.
The True Pacifist Route ends with the barrier being broken, and the protagonist and the monsters of the Underground being able to leave. Additionally, this route will feature the True Pacifist Ending Credits.
- For a more detailed explanation of this route, see Genocide Route.
Completing the Genocide Route leads to the destruction of the game's world. Upon re-launching the game after a completed Genocide Route, the first human asks the protagonist to give up their SOUL to them in exchange for the recreation of the world. This effectively acts in the same way as a true reset, but it also permanently alters the endings of any later Genocide or Pacifist endings (Soulless Genocide & Soulless Pacifist). Neutral endings after a Genocide run are unaffected.