Undertale has three different main endings (Neutral, True Pacifist, and Genocide) and a fourth miscellaneous ending (Hard Mode).
- The protagonist does not befriend all plot pivotal characters (Papyrus, Undyne, Alphys).
- The True Lab has not been explored.
- The protagonist kills any, but not every, 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
- A Neutral Route has been completed. (A reset is not required, only reloading the player's SAVE file afterwards.)
- No monsters 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.
- The True Lab has been explored.
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 features the True Pacifist Ending Credits.
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 from the True Pacifist Route, but it also permanently alters the endings of any later Genocide or True Pacifist endings (Soulless Genocide & Soulless Pacifist). Neutral endings after a Genocide Route are unaffected.
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