Multiple Endings / Undertale

Undertale has three basic variants to its ending, though the phone call at the end of a Neutral run has several sub-variants of its own. None of these have official names; these are all fan nicknames.

Neutral Endings

These are basically the default ending, you get this if you don't qualify for the other two. First, you fight Asgore. Then, you can kill him or spare him — but if you spare him, Flowey kills him himself, and then shatters his SOUL either way so you can't use it to escape the barrier. Then he steals the human SOULs and goes One-Winged Angel to fight you as Photoshop Flowey — unless you've gotten this ending before, in which case he figures, why bother? Either way, you end up outside the barrier, somehow, and much later, you receive a phone call from Sans.

• "Family Ending", also known as the "Toriel Ending" or "Neutral Pacifist": Don't kill Toriel, Papyrus, or Undyne, and don't kill more than 10 Mooks.^note Keep in mind: you cannot kill any mooks at all if you want to befriend Undyne. You also cannot befriend her if you deny her water after your battle, with the game implying that she has "fallen down" (is gravely ill, possibly dying) as a result. Toriel takes over as queen, and makes a policy that humans who fall into the underground are to be treated as friends, not enemies. She also disbands the Royal Guard (except for Papyrus). Minor dialogue changes occur if you hung out with Papyrus and Undyne, killed anyone after hanging out with Undyne, killed Mettaton, or hung out with Alphys:
  • If you went on the date with Papyrus, he takes the phone and mentions being the new Captain of the Royal Guard, though all they do is water the flowers in the Ruins. He mentions that Undyne is helping Alphys try to breach the barrier.
  • If you hung out with Undyne, she takes the phone (after giving Papyrus a noogie) and tells the player she doesn't blame them for Asgore's death.
  • If you went on the date with Alphys, she takes the phone and elaborates on her efforts to breach the barrier. If you reach this, and also spared Flowey, then Flowey specifically mentions you should go back to the True Lab for the Golden Ending. But you can achieve that without fully resetting the game whether you spared Asgore and/or Flowey or not.
  • "Vengeful Undyne Ending": If you play a Neutral Pacifist run so you end up befriending Papyrus and Undyne, then kill even a single monster (besides Mettaton, Asgore or Flowey) after befriending Undyne (but still less than ten), she is beyond upset that her trust has been betrayed, and Papyrus recommends the player doesn't return, because he's certain Undyne will kill them if they do. If you achieve this ending, then you need to do a reset to get the Golden Ending.
  • "Despondent Undyne Ending": If Mettaton is the only boss you killed, then Undyne mourns the missing/presumed dead^note It's implied she was Driven to Suicide Alphys. Papyrus recommends she go looking for the player for revenge (as an excuse for him to see the player again), but Undyne can't even bring herself to do that, as it won't bring Alphys back.
• "Exiled Queen": Don't kill Toriel, but do kill either Papyrus, Undyne, or at least 10 Mooks. Toriel tries to take over as queen, but is overthrown by monsters who hate humans due to your actions. If you didn't kill Undyne, she spearheads the revolution. Otherwise, Toriel simply realizes her policy is unwanted. Either way, she retreats to the original Ruins and leaves peacefully.
  • If you didn't kill Papyrus, he and Sans split time with Toriel watching over the Ruins in case another human falls. Papyrus mentions he'll be a great mom.
  • If you killed Papyrus, Sans says he doesn't have the heart to tell Toriel that you killed him because she protected you, and tells you that you're not welcome to return.
• Undyne ending: Kill Toriel, but not Undyne. Undyne takes over and plans to wage war against humanity. Sans mentions he tries to visit Toriel, but she doesn't respond anymore.
  • If you didn't kill Papyrus, he interrupts and gets the phone before Sans puts two-and-two together. Undyne assigns him to "The Most Important Royal Position", which consists of standing around and looking cute.
  • If you did kill Papyrus, Sans reasons you killed Toriel as well, and tells you that things do not look good for you.
• Mettaton ending: Kill Toriel and Undyne, but not Mettaton. Mettaton takes over as king and makes the underground into his Egopolis. Mettaton does concede he feels bad about how he treated Alphys, but could never find her to apologize, so he built a statue in her memory. Sans and (if you didn't kill him) Papyrus are his agents, which Sans thinks is ridiculous but Papyrus thinks is awesome (though he is disturbed by some of the darker aspects of Mettaton's reign).
• Papyrus ending: Kill Toriel, Undyne, and Mettaton, but not Papyrus. Papyrus becomes king, by process of elimination. He seems to be doing pretty well by just telling everyone to work hard and making spaghetti for them, but it's implied that Sans is doing the real work.
• Annoying Dog ending: Kill Toriel, Papyrus, Undyne, and Mettaton, but absolutely nobody else. Somehow, a small white dog becomes the ruler of the Underground. It spends all its time sleeping on the throne and does absolutely nothing important. Somehow, this works out pretty well.
• Anarchy ending, also known as the "No Mercy" Route: Kill Toriel, Papyrus, Undyne, Mettaton, and at least 1 Mook, but don't go full Genocide: With the death of everyone important, the Underground descends into despair. Sans laments that this is what happens when people like him take it easy. If you killed more than 20 enemies, he also chews you out for that and tells you to go to hell.
• Alphys ending: Abort a Genocide run by not depopulating the Hotlands + CORE area^note The actual coded requirement is to kill Toriel, Papyrus, Undyne, and Mettaton, and have a "murder level" of at least 12 but below 16. The murder level calculation makes it clear that this is the only way to do that; specifically, murder level 12 is reached by killing Undyne the Undying, at which point the only ways back onto Neutral for this ending are to spare the Royal Guards 01 and 02, spare Muffet, or fail to exhaust the random encounters in Hotland and the CORE. In all cases, you will face Mettaton NEO, who cannot be spared.^{further note}Activating the No Mercy route, but aborting before Papyrus or Undyne, only moves the player to the applicable Neutral route.: Sans hands the phone to Alphys. She mentioned Undyne called her in desperation, and that motivated her to do something about your murder rampage. She hid as many surviving monsters as she could in the True Lab (acknowledging she would have to reveal her secrets in doing so), and for what she does (and a lack of better candidates), the monsters elect her as their new leader. She only called to tell you she hates you for what you did, and laments that she should have killed you when she had the chance.
• "Dirty hacker", or "error handler": This ending can't actually be reached; every possible game state will somehow lead to another one. If you COULD reach it, Sans would admit that he has no clue how you did it, and suggest telling Toby how you got there — but then admit you're probably only seeing it because you hacked the game.

True Pacifist Ending

The so-called "True Pacifist" is considered the Golden Ending, though the naming screen Easter Egg indicates it was probably supposed to be something like "mercy run". After getting a Neutral ending and sparing Flowey, he'll give you a hint as to how to get here — kill 0 enemies, and hang out with Papyrus, Undyne, and Alphys. You can't actually hang out with Alphys unless you've gotten a Neutral ending, which ensures that you can't get this ending first, but if you killed 0 enemies and gave Undyne the water, you won't have to reset, just reload. You go through the True Lab and learn of Alphys's failed experiments, and how Flowey came to be. Then, when you face Asgore, Toriel interrupts the fight and tells the two of you that there will be no killing today. All of your friends gather… putting them in place for the final boss to take advantage of them. Flowey appears to steal all of their SOULs. With six human SOULs, and the SOUL of every monster in the Underground making up for the seventh, Flowey can finally take on his true form — Asriel Dreemurr. After an intense fight, you save all of your friends' souls, allow Asriel to make peace with himself and you, break the barrier on the underground, and live a life with all your friends, and every monster on the surface in harmony with humans. You either live with Toriel taking care of you, or remain in contact with her as friends. Arguably the true ending, as it's the only one with a credits sequence.

No Mercy Ending

The "Genocide" or "No Mercy" route^note Not to be confused with the Anarchy/No Mercy Neutral path above, occasionally called "Max LV" or some variant on "a bad time", and the naming screen Easter Egg indicates it was probably meant to be called something like a "murder run". In each of the four areas (Ruins, Snowdin, Waterfall, Hotland+Core), kill Random Encounters until the Anti-Grinding kicks in, making sure not to miss any Unique Enemy, then kill the boss. The tone of the game changes wildly, and every boss except Undyne goes down in one hit. Save points outside the Ruins just read "X left", and then "Determination" once you've killed them all. The monster history sequence in New Home is replaced with Flowey explaining his personal backstory. He caps it off by saying he appreciates you because like him, you're the kind of person who'd just kill anyone who got in your way, including him. Then he realizes, Oh, Crap!, you're probably going to kill him. Sans's judgement in the Last Corridor is replaced with an incredibly difficult boss fight, and when you finally overcome him, you kill Asgore in one hit and brutally murder Flowey. Then the Fallen Child appears. They explain that your actions convinced them that their Unexplained Recovery was a chance for them to kill the enemy and grow strong, and now that you've killed all enemies, it's time to destroy this world and move on to the next. (This means to move on to the next video game. After all, you're done with this one, right?) You don't get a choice in the matter. After getting this ending the first time, the entire game is replaced with a blank screen. If you wait 10 minutes, the Fallen offers to restore the world, if you give them your SOUL. This lets you play the game again, but permanently alters both the Golden Ending and the No Mercy ending. If you kill everyone again, the Fallen Child is baffled that you'd do so after selling your SOUL to restore the world, since it was doing this once that necessitated that exchange in the first place. In fact, they're so baffled that they restore the world for free and tell you to take a different path next time. If you do take a different path and go for the Golden Ending, the very last scene gets a Stinger reminding you that the Fallen is the one in control now, and implying that they're going to kill them without you.