Released in 2015, Undertale remains one of the best indie games in recent history. This friendly and amazing RPG was all about exploring the underground world of monsters and making choices on whether or not to befriend them or use violence to get what you want. The game also paid tribute to a wide array of classics such as Earthbound, and like those older games, it features a wide variety of secrets.
Undertale is, in fact, famous for its secrets, as there are an incredible number of them across the various different versions of the game on both PC and console. From hidden villages to mysterious scientists to ominous followers, let's now take a look at secrets from Undertale that you may not have known about.
Updated February 3rd, 2021 by Hayley Mullen: A game like Undertale is often chockfull of secrets, so a simple list of 10 just doesn't cut it. Fans have discovered more and more about the instant-classic ever since its release, including some Easter eggs most players won't ever encounter during their playthroughs of the game, such as rare phone-calls and special dialogue related to items. While you're waiting patiently for Deltarune to come out, let's take a look at more you might not know about Undertale.
15 Temmie Village
First on our list is the isolated Temmie Village, a secret settlement of Temmie monsters hidden off the beaten path in the Waterfall region. It takes a bit of work to find this place, as you must walk down an invisible path to reach it. There are a few hints in the dialogue from other characters, but otherwise its up to you to make your way here.
Temmie Village is full of Temmies (naturally), each of whom have unique and humorous dialogue. The Tem Shop here is also the only place in the game that lets you sell items in your inventory. You can also eventually purchase the Tem Armor here - the best armor in the game.
14 Mad Mew Mew
Secret boss fights are always a neat secret to find, and Undertale has quite a few of them. For this fight, you'll need to own the Nintendo Switch copy of the game, and interact with a few things in Papyrus's house before uncovering the route to Mad Mew Mew.
The boss fight itself is tricky, as it introduces a new mechanic where the player's soul is split in two and you must move each half independently to the correct positions. You can't actually hurt Mad Mew Mew, and must instead survive long enough to spare her.
13 Shyren The Star
Upon entering Waterfall, players will be accosted by the unique monster, Shyren. To spare her, all you need to do is encourage her to follow her singing dreams, which unlocks the option to end the fight non-violently.
For players who want to do more, though, continuing to encourage Shyren sees her becoming bolder and more confident. Her attacks (or rather, her songs) become faster and harder to dodge, but you'll get to follow along as she eventually winds up performing on stage.
12 So Sorry
Not all of the secret boss characters in the game are console exclusive. Anyone with a copy, be it PC, Playstation, or Switch, can find this next entry. You'll need to find the Art Room in the Hotland region which then leads the player to bump into this artist monster, kicking off the fight with So Sorry.
So Sorry has several "attacks" based around the monster clumsily trying to share their art. Sparing the creature leads to a series of humorous dialogue lines, whereas trying to kill them has its own set of equally amusing exchanges. Either way, this boss is still a fascinating find.
11 Hard Mode
For reasons that are explained at the end of a Pacifist playthrough of Undertale, the canonical name of the game's protagonist is Frisk. For those same reasons, naming your character Frisk at the start of the game could absolutely lead to some serious problems. It makes sense, then, that doing so unlocks the game's Hard Mode.
Hard Mode is pretty short, lasting only till the end of the Ruins section. New monsters, as well as monsters from later in the game, can be encountered here, and there are numerous changes to how other elements in the game world work as well. It's not for the faint of heart, although it is certainly an interesting experience for any who want a bit of a challenge.
10 Gaster
What may be (somewhat ironically) one of the most well known secrets of Undertale is the existence of WD Gaster. This character is only very rarely mentioned, as the characters associated with him show up randomly and talk about him in evasive, uncertain dialogue.
You can actually find him in the game as well, although he appears even more rarely than the characters that mention him. When he does show up, he can be found by going through a nondescript door in Waterfall, and he disappears the moment you attempt to interact with him, making WD Gaster the most mysterious secret in a game chock full of secrets.
9 Special Character Names
Along with getting a special response when the player calls themselves Frisk, there are unique results for almost every character in the game. Forbidden names, such as Flowey and Sans, will result in dialogue presumably from those characters saying "I already CHOSE that name." and "nope." and prevents the player from using the name.
Allowed names such as Gerson generate answers like "Wah ha ha! Why not?", and Papyrus gets incredibly excited to see his name being used and cuts off the player half-way through typing, resulting in "Papyru" as their name. Most interesting is typing the name Gaster, as it actually crashes the game or sends it back to the title screen...
8 Spare Text Color
It's good to talk to as many characters as possible in Undertale; not only will you have a better time playing the game and enjoying the story, but you'll discover Easter eggs and mechanics that are pretty neat and often overlooked by others. By talking to the third Froggit in the Ruins area, the player can make the game more difficult by removing the yellow text that appears when a monster can be spared.
This is a fun added level of difficulty, but if you find yourself struggling, talking to Froggit again can get all of the monsters to start using pink text, since they all threw out their yellow spare text.
7 Stick Item
Another one of the endless Easter eggs in Undertale is the Stick, an item that can coax several different responses out of several different characters. The Stick is found at the very beginning of the game and is functionally quite useless, especially as an actual weapon. However, it's worth holding on to for the funny results you'll get during your playthrough.
Throwing a Stick for any dog character will make them instantly spare-able, which is adorable. If the Stick is thrown during the battle with Papyrus, he will actually fetch it. Throwing the Stick during the Mettaton EX fight will nab the player 700 or more points, depending on when they throw it.
6 The Wrong Number Song
One of the many phone calls the player can receive in Undertale is the wrong number song, a cute little song sometimes encountered at the Snowdin River person dock before reaching Hotland. The person on the line asks "Can I speak to G..." before cutting themselves off and performing the song.
Some players have theorized that the caller is asking for Gaster. Interestingly enough, this song only plays when the game's fun values are low (between 2 and 39), too low to encounter any characters related to Gaster or Gaster himself. Perhaps there's a second meaning to "wrong number" in the song?
5 Hotland Tree
Because of Undertale's retro charm and character, the game's popularity only grows with every passing day, players have basically done every possible action to try and discover every tidbit the game is hiding. One of said tidbits is at the beginning of the Hotlands, where a water cooler is stationed at the end of the bridge.
This water cooler is primarily used to give (or deny) water to Undyne, who passes out from heat exhaustion, but in a True Pacifist route, life can be created as well as spared. If the player gives water to Undyne and pours the rest of the water out onto the ground, a small tree will be found growing there at the very end of the game. Looks like Frisk has a green thumb!
4 Flowey The Stalker
The first character you'll meet in Undertale is Flowey the flower, a smiling little daisy that almost immediately tries to kill you. Flowey pops back up periodically throughout your game, commenting on your actions and how you've been playing. However, he actually shows up much more often than most people realize.
If players stop suddenly and then quickly backtrack, they may be able to catch a glimpse of this homicidal plant before it shrinks back into the ground. This explains how Flowey always seems to know where you are and what you've done - he's following you, which somehow makes his character even creepier than before.
3 The Dog's Room
This area is quite a challenge to reach, as it requires some serious skill to unlock. You'll need to complete the game on a Pacifist run, sparing every single monster in order to unlock the true credits. Then those credits will animate and start flying towards you. If you manage to dodge all of them, then restart the game, this small area in Snowdin will be available.
Inside is the Annoying Dog, which is generally accepted to be a metaphor for the game's creator, Toby Fox. Interacting with the dog and items around the room lead to some fourth wall breaking jokes and comments about the game, such as fixing bugs. It's a nice little Easter egg for anyone who wants to put in the effort.
2 Glyde
The final secret boss on this list, Glyde can be encountered in roughly the same area as the Dog's room from the previous entry. You'll need to head to the room with the locked door in Snowdin, and then consistently keep moving in that area. Eventually, you'll encounter Glyde.
This monster is extremely arrogant and repeatedly makes references to its supposed coolness. Defeating it can be done either in the standard way of attacking it until it dies, or by applauding twice, then ignoring it. The latter option will eventually cause Glyde to leave, looking for praise elsewhere.
1 Sans' Room
This next entry can only be obtained during a Pacifist route, and can take a long time to pay off. You'll need to play nearly the entire game, to the point where you reach the hall where Sans judges you for everything you've done. Once the encounter is over, you'll need to reload the game and do it again — and then again.
Repeating the process enough times leads Sans to give you the key to his room back in Snowdin Village. You can return to the area, then enter to find a few mysterious hints at Sans's past. There's nothing definitive there, but its does help further some of the stranger conundrums of the character.