When starting up the game for the first time, you should really see the opening cinematic if you haven't before, as it tells you a bit of the plot before the game itself takes the reins. You should be able to see the button commands on screen before starting a new game, as well as the Settings menu to change them if you feel like it. There are also a few borders you can choose from that, when selected, will be placed around the game when you play. More will be unlocked as you progress, but Dynamic is generally a nice choice (if you want to use a border) because it changes over time.
Whenever you're ready, start your new game by naming the fallen human. You have six characters maximum for this name. Certain names cannot be chosen for various reasons, but you'll very likely not know these names until after you're playing the game. After confirming the fallen human's name, the game will begin.
You will wake up on a field of flowers with light from the surface shining from above. Now may be a good time to look at your stats with , just to check out the menu. Walk on the only path ahead until you reach a flower. He seems friendly, and he'll even talk to you about how the game works a little bit. Your LV, which stands for LOVE, can be increased by collecting friendliness pellets. He'll send you some to start the game off. Go ahead and try to get as many as you can from this first little group.
Flowey will give you a final piece of advice before surrounding you with more pellets, but before they can reach you, a woman named Toriel will come to save you. Follow her to a purple, ruinous room, where you'll find a yellow sparkle by some petals. Points like these are how you save, and they also double in fully restoring your health. No need to use them sparingly; it's best to use them whenever you see one. Toriel will give you a few switches to pull as she leads you out of here.
Tutorial With Toriel
A short ways in, Toriel will tell you that monsters may attack you in the underground, and she'll want to prepare you for it. Talk to the training dummy and assess your options. FIGHT leads to an attack, where a bar will quickly glide across the screen; you'll want to stop it in the middle of the bar's oval area for more damage. ACT will often lead to a set of more passive options, like checking an enemy, talking to them, etc. Doing this will allow you to spare an enemy, which is done in the MERCY tab. MERCY can also be used to flee from battle. ITEM is, of course, where you use items, but you don't have any right now. FIGHT or ACT with the dummy however you please.
Note: The two main variations of the game's playstyles, Pacifist and Genocide, are related to fights. Killing no enemies will result in a Pacifist playthrough's ending (as long as you do other events as well), but killing so much as one enemy will reduce a run to a Neutral route. In this case, you'll have to replay the game to aim for a Pacifist ending. The Pacifist route is an extension of Neutral, and therefore Pacifist gives you more of the game to see and play. A Genocide playthrough involves killing absolutely as much as humanly possible, but this run is so much different that it's been given its own page. A Genocide playthrough generally works better storywise after seeing the Pacifist ending through anyway.
There is no "best" way to experience the game, despite what people tell you. People who have played the game before will sway you into playing a certain way, be it Pacifist on your first run or otherwise. Be aware that the game was designed to let you do whatever you feel like (even though certain endings will affect other endings somewhat). Even the trophies don't make you do anything a certain way.
Note: The walkthrough will provide advice on how to achieve a Pacifist run, as a Neutral run is pretty straight-forward. Pacifist runs revolve around ACT commands, and since FIGHTing is pretty obvious, there will be a fair length of information around ACTing. Ignore these if you just don't feel like doing a Pacifist run, of course.
Defeating the dummy with attacks will not negate a Pacifist run, as defeating it doesn't provide EXP. Talking to the dummy wouldn't be very fruitful either since it doesn't have a way of talking to you. On your way through the next room, a Froggit will attack you. Spend a turn however you wish, as the fight will end prematurely here anyway. As for the next puzzle, a slate on the wall will tell you how to solve it. Take note of the western room before talking to Toriel and trying to make your way across.
In the next room, Toriel will ask you to get through this entire room by yourself. Try not to get lost or mess this up. As a reward for getting through to the other side, Toriel will give you a cell phone, which has been added to your menu. You have four options to talk to Toriel with if you decide to call her. She'll be calling you in the next room, though. A peaceful Froggit stands by a door to the north that leads to a bowl of candy. The bowl says to take only one, but you know how this always goes. Nobody is stopping you from taking as much as you please. If you take as much as you can, you'll have four more trophies.
On Your Own
The room with the Froggit and a save point is where you'll truly come across random encounters. It might be a good idea to become accustomed to them here. Froggits and Whismuns may appear here. Whismuns can be spared immediately, all of the time. You can also console a Whismun to make it run away before you can even try to calm it down. Threatening or complimenting a Froggit will result in it being scared or flattered, allowing you to spare it.
During the enemy turn, all enemies will attack at once, but usually at an easier rate than when that enemy is alone. As such, if facing both a Froggit and a Whismun, it may be wise to spare the Whismun to get it out of the way. All attacks should be fairly easy to avoid anyway, which is done by moving your SOUL out of the way during their attack. Don't be too worried about being damaged since a save point is so close by. In the next room, the floor will collapse when walked on; just use the door you find to reach the other side.
Toriel will ask you if you prefer butterscotch or cinnamon. Answer truthfully, as this will affect something else later. After pushing a rock onto a switch, You'll reach a room where all of the floor is collapsible if stepped on in the right places. Unfortunately for you, the only way to see the correct path is to fall down and see for yourself. Reach the other side at your own pace. Past this is another save point, some cheese, and a mouse hole. Check out the mouse hole with for a trophy if it doesn't pop by your reaching this room.
Reach the mouse hole in the Ruins.
A ghost will be pretending to sleep up ahead. Move it with force to engage in a fight. If you're trying to spare Napstablook, the only ACT command that will make any difference is Cheer, but you're free to check the other commands if you're curious to see what he says. Cheering him on will work to improve his mood. Do this a few times to end the fight peacefully.
If you go straight ahead, you'll come across a spider bake sale, with the proceeds going to real spiders. Grind out some money if you'd like the more expensive item (it's only 18G); whichever item you buy (if you decide to buy one), save it for later. It'll come in handy if you use it at the right time.
In the next area is an enemy called the Loox; check him in battle for his family name. To spare a Loox, you should don't pick on it. Picking on it will make its attacks more volatile. The Migosp is very angry but can be spared as soon as it's alone. Moldsmal, a gelatinous enemy, can be spared immediately; however, flirting with it first can provide you with 1G as part of the battle reward. Also in this hall are some Froggits that will remind you of some gameplay elements, like the screen border and the fact that enemies you can spare have their name changed to yellow. If you don't particularly like yellow, talk to the Froggit on the right about it.
The upcoming room has only one switch but has six holes to fall into. The southwest hole has a faded ribbon that can boost your defense. The northwest and southwest hole contains a Vegetoid, a new enemy. You can try talking to it if you'd like. A Vegetoid can also be devoured, but only if it's been damaged enough. Since this is probably a pacifist run for you, that's off the dining table as well. The last option you have is just Dinner. Use it and eat your greens to spare the Vegetoid. By looking at the other rooms, you should be able to see the switch in the upper-middle hole.
You'll then come across a room with many small, colored switches. Keep in mind where these switches are in this first room, as the next room is a 90-degree clockwise rotation of the same room. Read the signs and press the appropriate switches to finish this puzzle. If you need help, the blue switch is always near the door you came from and the red is always farthest away.
Now that you've finished the last puzzle in the ruins, continue east to find a Froggit and a door leading to a new weapon (and a view of the city). Although weapons seem very pointless on a pacifist run, it's still wise to replace your weapon with better ones you find along the way. Walk to the north from the previous fork in the road to get to Toriel's house.
Toriel will tell you the type of pie she ended up making, and depending on your earlier choice, you may be surprised to see what you get. Follow her down the hall, where you'll be able to check out your room and just about everything else down the hall; even checking the mirror has a message for you. Hop into bed when you feel like it and pick up the slice of pie Toriel left for you. Like the spider food, this too is an item you really, really ought to save for later. Talk to Toriel about how to leave the ruins. When she leaves, follow her downstairs.
Toriel wants to destroy the door leading out of the ruins for your own sake. Apparently, all humans that have fallen down the same hole as you have been killed by ASGORE. Stay on the path and follow her to the door, leaving her no choice but to confront her. Work on sparing her about eleven times or lose enough HP and Toriel will weaken her attacks. There's no need to use any of your healing items for this fight. Continue to spare her until she decides to let you through the door. Pass by a flower in the middle of your path before you truly leave the ruins.
As you walk away from the ruins, you may notice something sneaking up behind you. It won't be long until it catches up. After it does, you'll soon meet a new character, Sans. He doesn't care about capturing humans like his brother does, so he'll offer to help you avoid detection for a little while. Sans will ask you to help cheer up his brother later, so you won't be hidden for long.
After this pseudo-introduction to Papyrus, You'll find a save point and a box. This box is very handy; you can put an item in it here and pick it up from a similar box anywhere else. For now, place your spider food, your stick (your first default weapon), Toriel's pie slice, and possibly Monster Candies if you'd like to save them for a hard battle. Already inside the box is a Tough Glove, a weapon stronger than the toy knife you recently obtained in the ruins.
You may encounter the Snowdrake in the screen with the save point. Wait for him to tell a joke so you can laugh at it, or heckle him so hard that he'll be upset enough to leave the fight. The Icecap enemy is also called Ice Cap interchangeably, much like the Zone in Sonic the Hedgehog 3. You can ignore an IceCap twice to spare it, but you can also steal its hat at that point as well. See what happens and compliment it on his looks if you do so.
Sans will introduce Papyrus to you. Shortly afterward is another guard post with a sign that says, "(Absolutely NO MOVING!!!)". Take its advice when you come across the guard, Doggo. Pet him when he isn't looking to make him go nuts. Continuing to pet Doggo results in more dialogue. Sans will tell you about blue attacks when you pass through that security checkpoint: When you see a blue attack, just don't move. You may also find an enemy called Lesser Dog here. Like Doggo, you can pet Lesser Dog to see what happens, but Lesser Dog will be far more gracious after the fifth or sixth pet. In fact, he'll appreciate every petting you can give him for quite a while.
North of the sign covered in ice is a snowman. He wants you to take a piece of himself with you to make up for the fact that he can't move anywhere. If you decide to take a piece of him, you can eat it right in front of him or put it in the box for later. Up next are a set of puzzles created by the great Papyrus; getting through the early ones shouldn't be anything you need a walkthrough for. Below are some things that will take place aside from the first few puzzles.
Papyrus's Puzzle Gauntlet
A Nice Cream man will be on the way to Snowdin Town. Nice Cream is a fantastic food item that restores 15HP. That's a big deal for someone who's only going to have 20HP for an entire pacifist playthrough. After getting through the puzzle Sans developed, you may come across a new enemy, Jerry. Nobody likes Jerry and for good reason. He sucks. He doesn't have his own attack, but he does make everyone else attack for two seconds longer than usual. The other monsters are easily willing to ditch Jerry if you pitch the idea (he'll come back after a few turns), but if you'd like to properly spare Jerry, tell it a joke if it's with the Snowdrake. Otherwise, you may just have to ditch this guy. If you do somehow end up with only Jerry at the end of the battle, ditch him.
Get to the Spaghetti save point in Snowdin.
You'll come across two dogs, the Dogi, consisting of Dogamy and Dogaressa. These two focus a lot on smell as opposed to sight. Roll around in the snow to disguise your human scent, then have them re-sniff you. Once you pet both of them afterward, they'll be astounded at the idea that a dog can pet other dogs. Later on, a challenging X and O puzzle may daunt you; as a last resort, there's a hidden switch in a tree here that can help you out. If you decide to press it, step on the main button again.
The final puzzle consists of many colored tiles, all of which have their own function. Here are the rules in a condensed spoiler tag for you to use, unless you feel like writing the notes down yourself.
If you find these rules to be too confusing even though they're here for you, you can ask him to re-explain them a few times for more clarity. Taking on this puzzle can be tricky; take your time with it to make sure you can get through it all. After finally getting through that puzzle, there'll be one more X/O puzzle for you to solve. It should easily be solved if you simply work your way from the outside towards the center.
You can now come across an enemy called Gytrot if you head south immediately after leaving this puzzle behind. This thing looks upset - and it is, for good reason. Someone's been putting decorations all over its antlers. Help him out so you can spare him.
Note: The reward for this fight is 120G, and it's recommended you do this to make a possible grind for money very soon much shorter than it needs to be.
Continuing on this path leads to a hidden room with a strange door; you won't be able to open it for now, and there are only a select few in the world who have legitimately managed to see what's inside. If you continuously move in this room for a long enough time, you can come across an optional battle. It can only happen up to a certain point, but you can head to Snowdin Town just up ahead for supplies if you want to be more prepared.
Monster candies are a great choice to use for healing items, as Nice Cream already surpasses them in usefulness and you may as well get rid of them soon. Snowdin Town, just up ahead, also sells healing items that surpass the monster candy. You can also sleep at the inn for 30/20HP.
Be careful, as this is the toughest fight in the game up to this point in terms of attack and attack power.
To spare Glyde, simply applaud him twice (he's done a pretty good job) and just don't do anything anymore after that. In fact, do nothing for the rest of the battle.
Before Snowdin Town
There are a lot of snow poffs on the ground once you get past the final X/O puzzle. If you check all of them, you can receive 30G (this can be repeated if you die and have to come back from the most recent save, but it's only 30G). The last snow poff is, in fact, a member of the Royal Guard like Papyrus. Greater Dog can be spared if you call him over and pet him. After that, of course, he'll want to play, and naturally, after playing, a dog would want to be pet a lot. Alternatively, ignoring the Greater Dog completely will bore him after a while. That's a lot easier.
You'll reach Snowdin Town after a short walk through one of Papyrus's puzzles.
You'll get your first chance to put the snowman piece away in a box, unless of course, you backtracked to the first box when you got it. There's also a shop here that you can buy a manly bandanna and healing items from, but make sure you still have over 350G if you buy a lot of things. You can also talk to the shop owner for more information about Snowdin Town.
You can also sleep at the Snowed Inn for 30/20HP. You'll also get to hear some monsters snore a melody in their sleep. Some may find that their snoring sounds like a bee flying around; bees they are - not. Since you weren't up in your room for very long, the lady at the desk will give you a full refund even though you got the health bonus. This place will always be free of charge, so don't forget about it if you want a free 30/20HP bonus.
There's a monster kid in the middle of town who will identify that you're a kid because of your striped shirt. He and other kids do wear striped shirts, so he has a point. On a northern path past Grillby's is a potential place to have someone dial the wrong number. Past Grillby's is the librarby, where you can read a bit more about the monster way of life.
Note: The opportunity to battle Glyde closes when you try to fight Papyrus.
Travel east of Snowdin Town until Papyrus stops you. To start, you should try to check, insult, and flirt Papyrus now before sparing him over and over. The one way you're going to win this fight is if you survive all of his attacks, so get ready for a bone tussle. After some time, he'll show you his famous blue attack. Act accordingly and jump over his bones to avoid damage. When it comes time for his special signature attack, something will go amiss, and he'll just use a regular attack.
Note: If Papyrus places you in a cell, just leave, heal up at the hotel, and try again. If you're really, really not having a good shot at this and lose to him three times, he may just let you go out of pity. Are you gonna let him take pity on you? You can try to fight him again until you spare him, or you can continue on ahead.
Once you've finished fighting Papyrus, befriend him, then go to his house and speak with him. At this point, you'll be able to take a tour of Sans's and Papyrus's house. Check out their closet to find another dog. The closet's back leads to the dog's shrine.
If you have at least 350G, then you can donate all of that to the dog shrine now so you don't have to come back later. If you do want to grind out money, IceCap gives 35G upon defeat if you steal his hat when he's been ignored for too long. There's also 20G in Papyrus's couch.
Donating to the dog shrine is a long and tedious process, as you can only donate 1G at a time. Whenever the donation box has reached its current limit, simply leave the room and come back to see what the money was used for. Keep donating until the box has been shut off and the shrine has reached full potential. A majority of Undertale's trophies come from donating to the shrine, so getting this over with now would mean that there isn't much left to do after this. The trophies are listed in the spoiler tag below to save space.
Note: The Switch version of this game has a shrine that appears to have taken place after the PlayStation 4 version. Information on the new content there will be covered in this walkthrough for those who own the two versions or simply want to see what happens.
Once you're done there, enter Papyrus's room and talk to him in there to start hanging out with him. After a successful session of hanging out, he'll suggest that you two be friends with his boss, Undyne. He'll also give you his phone number. Continue east to get to the waterfall area.
Shortly after entering this area, you'll come across Monster Kid and Sans once more. Monster Kid is here to see the ultra-cool Undyne and Sans, if you convince him, will order some food at Grillby's with you. Past his stand is a waterfall with rocks flowing down it. If you get pushed off, you'll simply have to walk back up to the top. An echo flower here hints at something behind the waterfall; go inside to find an old tutu, a great defensive boost.
After using some bridge seeds for the first time, you should find Aaron. Challenge him to a flex-off to get him going. After enough flexing, he should be completely flexed out. After this is another bridge seed puzzle; consider using them to go to the southeast if you'd like to see what's down there. If you mess up with your seeds, ring the bell in this room to reset them.
You may come across Woshua later. It wants the whole world to be clean, so you may as well ask it to start with you. Check out the telescope you see in the wishing room to look at the rocks in the ceiling. After another save point, try heading west past two conversing echo flowers to find a patch of grass. Inside the grass is a pair of ballet shoes, a new weapon. If you find Shyren, you may notice that she's having a hard time with her singing abilities. Try to get her going by humming with her.
You'll pass a room with a piano that is rumored to hold a great treasure inside, as well as a statue with horns. If you take an umbrella from the next room and give it to the statue, a melody will play; melodies are played on pianos, so try jamming out on that piano. (Press to play a note.) You'll find a legendary artifact in the room you open up. After some mishaps, you'll be given dog residue. Using dog residue fills your entire inventory with dog residue (and occasionally dog salad). Dog residue can sell for a varying small amount of G, and dog salads can restore random amounts of health. Congrats! You now have an infinite resource to sell. If only you knew a place to sell them. Don't throw your last dog residue away; if anything, make a spare dog residue and put it in your box when you have the chance.
Continue onwards to find Monster Kid in the rainy part of Waterfall.
Reach the place where it rains.
Trash and Rain
Undyne will attack with spears once more, leading your arrival into the trash zone. You'll find a ghost possessing a dummy, much like before, who is very upset with you about the way you treated its cousin at the start of the game. Dummies don't take damage from you, so you'll just have to find a way to redirect its attacks into itself. After the battle, Napstablook will offer you the chance to hang out at his place. You can lie down on the ground with him if you'd like. Additionally, if you play his Spooktunes CD and leave his house, you may come across Aaron and Woshua, who will really hate this music. Aaron can now be shooed away after hearing the ghost's very scary tunes.
Up ahead is a shop ran by Gerson, an old-timer who took place in the monster-human war. His defense item isn't really that great but makes up for giving you more invincibility time after being hit by an attack. The weapon he sells does the same thing, and since you're not attacking on a pacifist run, it might be a good idea to buy it.
Moldbygg comes into battles after passing Gerson's shop. Try to unhug the thing. Afterward is a dark room, where the paths only light up if you touch the glowing mushrooms along the way. Try to go south when you're in the southeast corner of the room.
In this place, all are Temmie. Except Bob. The Temmie running the shop needs 1000G to go to college. If you really want to, you could sell dog residue to it until it has enough to pay for college. Realistically, that doesn't make any sense, but it works. If you want to help it pay for college, make sure you keep a spare dog residue in the box just in case you accidentally sell your last one.
After paying for Temmie's college, Temmie will sell Temmie Armor. This is the strongest defensive item in the game that you can use, but it really makes combat uninteresting as a result. Its starting price is 9999G, but it can be lowered to a minimum of 750G if you die enough times. Only buy this if you're having a bad time with a particular battle (or you just want to see how strong it is).
After walking through more of Waterfall, Monster Kid will slip and dangle off a bridge. Help him up and make your way to Undyne, who will finally challenge you. You're given the opportunity to save and heal up before the fight so you don't have to walk back here every single time. When fighting Undyne, she'll use her spear to turn you green. Green gives you one side to protect yourself with as she throws spears at you. Gold arrows will spin the other way around. In order to progress, you must continue to escape the battle when your SOUL is red.
You'll make it to the border between Hotland and Waterfall when Undyne's armor heats her up too much. Give her some water from the nearby cooler to help her get back on her feet. There's a save point in the next room, and you can go south from there to return to a point in Waterfall much closer to her house. As Papyrus mentioned when he called you during your escape, he thinks the three of you should hang out at her house. Take the ferry to Waterfall and head left when you see Gerson's shop to find the area Undyne lives in. Papyrus will be outside her house.
Talk with Undyne until Papyrus tells her that she's not up to the challenge of being your friend. This will prompt her to have a massive urge to prove him wrong, so she'll make you some food after you take a seat at the table. Other events will transpire afterward. After the entire bout of hanging out with her is over, you can find her in Snowdin Town with Papyrus, but you're headed into Hotland. Take the ferry back to Hotland and go inside the lab at the area's entrance.
Inside the lab, walk to the right to meet Dr. Alphys, the royal scientist. She'll tell you in advance that she made Mettaton, a robot for entertainment with anti-human combat features, but after watching your entire adventure, she wanted to disable those features. A problem has arisen, and Mettaton has a lust for your blood. He'll make an entrance fairly soon; you might recognize him to be similar the contraption Papyrus used for his color puzzle so long ago. He'll start a fight with you right after he explains the rules of his quiz show.
Mettaton's maximum defenses make him completely impervious to any sort of attack. Below in spoilers are the answers to his questions, should you decide to use them. Alphys can help out too, so don't ignore her in this fight. There are a lot of questions. Crying in the Act commands might be worth a shot.
What's the prize for answering correctly?
What's the king's full name?
What are robots made of?
Two trains, Train A, and Train B, simultaneously depart Station A and Station B. Station A, and Station B are 252.5 miles apart from each other. Train A is moving at 124.7mph towards Station B, and Train B is moving at 253.5mph towards Station A. If both trains departed at 10:00 AM and it is now 10:08, how much longer until both trains pass each other?
How many flies are in this jar?
What monster is this?
Would you smooch a ghost?
How many letters in the name Mettaton?
In the dating simulation video game "Mew Mew Kissy Cutie" what is Mew Mew's favorite food?
Who does Dr. Alphys have a crush on?
After finishing the quiz, Alphys will update your phone to include texting and a bunch of other features. A particularly fantastic new feature are the two Dimensional Boxes you can access from your phone. Box A holds items from the boxes you've already come across, and Box B is exclusively phone storage. You're free to check out the upper area to her lab and the box at the end of the conveyor. It might also be worth saving at the save point from the side of the lab you came from. Continue out of the lab and check out three of Alphys's social media posts to reach Hotland proper.
In the first chunk of Hotland, it's possible to encounter Vulkins and Tsunderplanes. A Vulkin can't take criticism very well, and it'd be wise to criticize it to stop it from attacking. After that, encouraging it or hugging it would work to make it happy, but the former raises its attack and the latter lowers your defense (basically the same thing - a pacifist approach doesn't use attack, though). As such, it'd be a bad idea to both encourage and hug a Vulkin before sparing it. A Tsunderplane, as the name suggests, isn't up for flirting with you, but as soon as you approach one, it starts to get nervous. Get close to its airplane attacks three or four times to spare it, but it'll also now be open to flirting. If you ever run into both of these at once, start by criticizing Vulkin until the Tsunderplane is dealt with.
Another save point appears when you reach a land of heat and clockwork. Pyropes may now appear - don't stare at their hot fire too long, or you might go blind. Their fire attacks might be an issue if you're not adept at moving in battle; their orange flames have to be moved through, the opposite of blue attacks. Cool Pyrope down to lower its attack (optional), then heat it up twice without cooling it down to spare it.
If you use the arrows on the ground, you can launch yourself with steam to another area. If you go off to the right, you can find a secret room that holds a burnt pan weapon. Its attack is -2 lower than the torn notebook you might have bought from Gerson in Waterfall. It makes up for this by adding +4 to HP from recovery items. If you're not sure if you want to use the pan, you can always put it in a Dimensional Box.
Alphys will call you in the room to the upper left of the steam arrow puzzle and will explain that orange lasers must be moved through, whereas blue ones require you to be stationary, just like combat attacks. Deactivate the lasers by pressing the button on the other side. Alphys will call you again once you approach three more arrows and will suggest that you go to the right first - the path to the north won't open until you solve the puzzles on the left and right.
The puzzle on the right is pretty simple; once you activate it, you'll see that you get two shots to fire in order to destroy the ship on the other side. Move the boxes around so that only one is between you and the enemy ship, then fire both shots. The left puzzle is intimidating, but you should only have to move the boxes up, left, down, and left again to get the arrangement you want. The door to the north is now open.
You'll soon find yourself in Mettaton's cooking show. There's a can of an ingredient you need on a high shelf, and it might take some time to reach. Mettaton will be throwing ingredients around to slow you down, but you should be able to make it to the can fairly easily if you prevent yourself from being hit by food too many times. Once you get it, you'll be safe for a little while longer. There's an elevator to the second floor of Hotland just up ahead. It can also take you to the left station of the first floor, which is the place just outside of Alphys's lab for convenience.
To the right of where you step off the elevator is Heats Flamesman. Remember his name for later. Sans is selling hot dogs here in Hotland for a pretty high price of 30G, and just past him is a long stretch of land between the elevator you came from and one on the left. The bottom path leads to a stained apron, which has a defense of 11 and heals you for 1HP every other turn. In the intersection between these elevators, however, is a hidden glass path to the north. If you come to this room on October 10th at 8 PM (or at any time on the Switch version), you'll run into a special monster named So Sorry. Finding him isn't required whatsoever, but if you feel like it, you can set your console's date to that time if you're not coincidentally here at that time. Some cases suggest that So Sorry can only be encountered once you reach a certain point later on, but I managed to trigger him with this being the farthest I've gotten in the game.
So Sorry is an artist, if you couldn't guess by the art club sign you have to read to fight him. Killing him does count against you if you're aiming for a pacifist run of the game. At one point in the battle, So Sorry will draw Doodlebogs with his magic pencil. You'll have to draw them a way out of the battle to keep things sane. After eleven turns of either attacking him or doing something else, the battle will end.
There are three switches to the left that have to be pressed within a short time of each other. Do so with Alphys's help until the path ahead is clear, then take a look at the mess of a steam puzzle in the next room. There are little panels with red dots next to the arrows here that change the direction of the arrows available. Use the panel with only an up and down arrow to change the upper left arrow to face left before reaching it.
The royal guards you may have seen earlier will attack you after realizing you're human. These guys are tough business, but Royal Guard 02's armor is filthy. Try cleaning it five times in the coming attack to properly clean it. This will make the armor more susceptible to heat absorption, making him take it off. Whisper to Royal Guard 01 to lead to a situation that'll end with the three of you leaving the situation fairly happy.
MTT News is the next channel you'll come across. Report on your favorite item in the room you're in and watch as Mettaton reveals his next plan. The bombs in the room will be flung all over the place and you'll have to defuse them all if you want to live. There are six bombs you have to defuse, so run around and try to find them all before it's too late. To defuse a bomb, use the Act command with proper timing. Take the elevator past this bomb room to the third floor.
Just at the top of the elevator is another bake sale, but this time, the items are absurdly expensive. Past this is another set of puzzles, one to the north and one to the south, that have to be solved to progress eastward. The solutions to these puzzles are in the spoiler below.
Two guys with diamond will state that their favorite Mettaton moments are when he beats up someone after they do a heel turn, or when Mettaton strikes a pose. This is kind of important information.
A spider lair is past the next save point. If you bought a spider cider or spider donut way back at the start of the game, pull it out of a Dimensional Box right now so it's in your inventory. A spider girl named Muffet will attack you for your hatred of spiders that they assume you have. Bribing her with increasing amounts of money will lower the damage she deals to you and struggling can lower the price of this, so if you really feel like lowering the damage, struggle when the price is really high. Then again, bribing does cost money that you might want to keep, so it's up to you. The battle ends after seventeen turns but ends very quickly if you use spider cider or a spider donut during the battle.
Muffet will turn your SOUL purple for the majority of the battle. This puts you in a state of movement that centers around lines, similar to sheet music. Because attacks have to follow three lines of movement, the attacks themselves can be very easy to dodge compared to other boss attacks.
Ahead of Muffet's lair is an opera song straight out of Final Fantasy VI. Well, the lyrics are different. After he drops you into the dungeon, he'll show you the puzzle he has in store for you. He won't explain it since you've seen something like it before, and you might have notes on it laying around if you made yourself a copy. After you try to get through, he'll drop down to fight you again.
Alphys has prepared a function in your phone that turns your SOUL yellow in battle, making it possible to shoot projectiles. All you have to do here is shoot him a few times, as that's all this battle is. Up ahead is a nice cream truck and the two royal guards, and to the left is a character from before. If you remember his name, tell him. North of the guards is the Mettaton Resort. Sans will offer to take you to dinner (which you should do), and you can also buy some items from some people in an alley to the right. That mystery key they're selling is indeed a key to a house in Waterfall. There's a burger restaurant inside the hotel and the door to the CORE is just north of the statue.
Hotland - CORE Branch
The elevator leading to the top of the CORE isn't working, so you'll have to take the long way up. The first enemies you'll find here are Madjicks and Knight Knights. Talking to a Madjick will invert your left and right controls, but it'll allow the Madjick to be spared instantly. You can also spare a Madjick by staring at either of its orbs two times total, or by clearing your mind and talking to it afterwards. A Knight Knight has to be sung to three times (or twice if you hummed with Shyren enough to learn her melody). When Knight Knight is asleep and you're wearing either the stained apron or Temmie armor, you can stall turns by doing something other than sparing her to build your HP back up.
With Alphys's help, you'll be able to make it to another save point. There are three paths ahead. There are different ways to open up the path to the center of the CORE, and you might come across different enemies along the way. One of these is the Final Froggit, which can be spared by mystifying it. A Whimsalot can be spared by praying and collecting a green butterfly (or praying twice). An Astigmatism will either want to be picked on, or it won't want to be picked on. You'll have to pay attention before it attacks as it speaks. Doing so will allow you to spare it. Additionally, challenging an Astigmatism will make Final Froggits and Whimsalots open to be being spared immediately, so if you find yourself in a battle with an Astigmatism with literally anything else, challenge it.
If you fight through the northern path, you'll have to face three sets of enemies to reach the switch to open the east end. If you decide to open the path to the end using the puzzle on the west side of the area, go with this:
Once you reach the end of the room, you'll find a save point and the elevator leading back to where you started, which now works.
Reach the second save point in the CORE.
If you happen to have the stick weapon, put it in your inventory. You won't be using it to attack, of course, but it'll be useful later. When you face Mettaton in the next room, get used to using the yellow SOUL mode to fire pellets at objects. Certain objects, like things that look like arms, can only be moved out of your way if you shoot their yellow target. Bombs will explode in a + shape when hit, so be careful. Alphys will eventually call you to tell you about a secret switch on Mettaton's back; turn him around and press it to make him vulnerable to attack, technically.
Flipping the switch turns Mettaton into Mettaton EX, a machine that technically take damage if you shoot his heart when it's open to attack. Coming out victorious against Mettaton in a pacifist playthrough requires ratings of 10,000-12,000 people watching at once, with the battle starting at 4,000. Throwing the stick now will raise the ratings by a good 700, but waiting until a certain point will double that amount. Putting on a different set of armor that hasn't already been worn in the fight will also raise the ratings by a massive 1,500. These are the two most notable oddities - the best way to raise the ratings is to boast. This raises the ratings throughout Mettaton's turn, but it stops and makes you lose 100 rating points if you get hit. That said, it's best to boast early on and save the special cases for later.
When it comes time for a pop quiz, the best answer you can write is "Legs", with the second-best answer being "Toby", the first name of the creator of Undertale. A disco ball can be hit to change its colors if a white line is about to approach you. If you're still not at 10,000 in ratings by the time you blast Mettaton's arms and legs off, throwing the stick will give you 1,400 points. It otherwise takes a rating of 12,000 total if his legs are still intact. The battle concludes once Mettaton has reached peak views.
Alphys will walk you to the elevator past Mettaton's room and tell you that she lied; it takes a human soul and a monster's soul to cross the barrier and return home.
Mad Mew Mew
People who own the Switch version of the game would be able to return to the Dog Shrine back in the skeleton brothers' house to find that the seal on the shrine has been broken. By moving the left and right stick away from each other, a secret battle with a catgirl doll will take place. Scratching it behind the ears will cause the ghost haunting the doll to burst out in laughter. She'll ask for a battle to release its emotions, which should let it fuse with the doll's body. All of Mad Mew Mew's attacks are dodged by moving the sticks in a certain direction to avoid being hit and should be fairly easy for someone who's made it far enough in the game to reach her. As the battle wears on, she'll tell you where she got the doll body and why she's so angry. After surviving enough attacks, she'll finally be able to listen to you talk to her without interrupting you. Show her what LOVE is - a pacifist would naturally want to show mercy.
As you approach ASGORE, creatures you've seen throughout the adventure will appear to tell you information pertinent to the underground. Grab a key from the house's kitchen and look in the bedrooms for two presents with pretty strong gear inside them, then get another key near the other bedrooms. Continue your walk until you reach a save point at the Last Corridor.
In this hallway, Sans will judge you for your actions throughout the game. He'll explain a few acronyms you might not know about:
This is a very important place in the game due to the fact that any boss you have encountered can be killed, removing them from the game. Populations of monsters in certain areas can also be killed off, which is also a factor. Of course, if you're playing as a pacifist as the name of this page suggests, you should not have killed a single monster.
Talk to ASGORE in the throne room. If you have Toriel's butterscotch pie, grab it from a Dimensional Box before approaching him later on near the barrier door. It'd also be wise to fill your inventory with good food items, of course. Use your best weapon.
At the start of the battle, ASGORE will destroy your option to show mercy. That means you're going to have to fight him, for real. Since you may not have fought before, it should be worth mentioning that attacking is done by pressing when the white lines meet up with the center of the attack screen. There are also two ways to weaken ASGORE's attack and defense:
- Talk to him three times (only if you've been as a pacifist)
- Use the butterscotch pie when you need to heal
Once you bring ASGORE down to low health, you'll finally be given the option to spare him. See what happens next for yourself, but try not to look further down the page too much.
After the events that take place in front of the barrier, the monster that showed up will take control of certain things. A battle will soon ensue against Omega Flowey, an incomprehensible and unfathomable foe. His attacks are very hard to dodge, but you're fortunately able to withstand quite a few before you die. Stay determined and persevere through Flowey's attacks as all six of the SOULs he's stolen are used as attacks against you. Find the Act command in these attacks and call for help to heal up and keep going.
A death keeps your battle progress saved, so don't fret too much about the difficulty of the fight. After calling the six SOULs to your aid, Flowey's defense will drop to nothing, making your attacks actually worth the effort. Fight and fight and fight until he's been stopped.
You'll eventually be given two options. If you want a true pacifist ending, you know which one to choose.
If you managed to complete the game without killing anyone at all, you should get a phone call after a short bout of credits. After this, someone will give you a clue about where to go next. Load up your save file and head on over to Papyrus's house - Undyne wants you to deliver something for her. Take her delivery to Alphys in Hotland and follow the events that take place. After the gang leaves, return to Alphys's lab yourself. Read the note on her floor and use the elevator nearby to reach a new area.
There are panels on the wall to give backstory to the position of the royal scientist, and what happened in this lab that led to certain events in the story. When you reach a new save point, you'll find that there's only one working way ahead. A note in a backroom hints at something being dropped down a drain. Check the sinks for whatever that item is - you'll encounter a set of monsters.
Memoryheads are a strange being. Perhaps they are an embodiment of evil or some kind of alien. Regardless of their origin, these things are technological in some way or another, and you'll only be able to understand them if you pull your cell phone out. Refuse their invitation to join them so you can spare them. The spared Memoryheads will drop a red key; use it on the machine in the back room and return to the chip dispenser you saw earlier. The door on the right is now open.
You should soon find a bedroom with a save point in it. One of the beds on the right side has a yellow key under the sheets. There's a path to the right that takes you to a bathroom that holds another amalgamate: Reaper Bird. The Reaper Bird is an amalgamation of an Astigmatism, a Final Froggit, and a Whimsalot. Because of this, it can be spared by mystifying it, picking on it, and praying once each. The end of the bathroom hall is the slot for a blue key, which is apparently in a cold place.
Return to the save point and head up and to the right to find the air conditioners. Put the stick in your inventory if you have it. Turn them on and face Endogeny, a conglomeration of a bunch of previously deceased dog monsters. To spare Endogeny, beckon, pet it, play with it, and then pet it twice more. Using the stick in this battle makes Endogeny immediately ready for sparing.
Save again to restore any health you may have lost before taking the upper path to the left. A pseudo save point holds the amalgamate Lemon Bread. Because this one is composed of Shyren's agent, Aaron, and a Moldbygg, you should hum, unhug, and flex once each. A room north of here holds the slot for the yellow key and a set of VHS tapes with a TV. These are worth checking out. Put the yellow key in its slot.
The room to the west holds a lot of fridges, one of which is the amalgamation of a deceased snowdrake's mother. Simply tell jokes three times to spare her. She'll drop the blue key after being defeated. After coming back towards the save point, you should find a room with a shower at the end. Check the curtain for the green key. Go back to the left and put the green key in its place, then return to the bathrooms and insert the blue key. Use the big door near the chip dispenser that required these keys in the first place so you can leave the lab.
You'll find yourself back at the stretch of land leading to the barrier. Go back to fight ASGORE. The rest of the game will be straight-forward enough all the way up to the credits. Here are some post-game spoilers of information you can use on later playthroughs.
After finishing the neutral playthrough (beating Omega Flowey), he will never appear again. From now on, he'll simply say that he won't bother fighting you if you're going to win, making future playthroughs faster. If you do want to fight him again, you'll have to remove your save data from your console entirely.
Now that you've truly beaten the game, you can try to play it again with new variations. This includes killing certain enemies, choosing different dialogue options, and so on. The next page covers the genocidal playstyle for Undertale, which is a much more difficult playthrough.