Underverse

At the beginning, you are placed in a random AU from Underfell

Underswap

Inktale

ErrorTale

Outertale

Aftertale

Flowerfell

Dancetale

Reapertale

Storyshift

Mafiatale (UTMob)

YandereTale

Underfresh

GasterTale

LittleTale

Undertail

Swapfell

Negatale

Poketale

Trainertale

Melontale

Chesstale

Fantastale

Dreamtale

Horrortale

Glitchtale

Dusttale

Grieftale

Ruintale

Sunnytale

Comictale

Multitale

OmegaTale

Coretale

StarTale

Darktale

Lighttale

MagicTale

Technotale

MythTale

Solartale

Lunartale

Frosttale

Embertale

Mirrortale

EchoTale

Frozental

Shadertale

Auroratale

Chronotale

anywhere but Underfell, you won't get into any other universe.

Glyde (Glowey / cut monster)

Biology: resembles the skeleton of a whale or dragon - large bones, no flesh.

Magic: Emits light, uses energy attacks.

Habitat: Lives in the mystical part of Snowdin, indicating a connection with magic.

Key similarities: bone structure as the basis of the body, magical nourishment.

Ghosts (in general, including Napstablook)

Biology: They have no flesh, they consist of ectoplasm and energy.

Magic: able to manipulate the environment, create illusions, pass through objects.

Longevity: They exist for centuries, as long as the memory of them remains.

Key similarities: existence outside the biological framework, dependence on non-material factors (memory, emotions).

Flowey

Biology: a plant with a face and “skeletal” facial expressions (grin, empty eyes).

Magic: Absorbs SOULS, uses their power for attacks and regeneration.

Immortality: Can be revived after death if he retains some of his power.

Key similarities: non-biological nature, dependence on magic and SOULS.

Boss monsters (Toriel, Asgore, Undyne, etc.)

Biology: Although they have flesh, their bodies are heavily magically enhanced.

Magic: They use powerful spells and have superhuman strength and endurance.

Longevity: Live for hundreds of years (Azgore has ruled for many centuries).

Death: When killed, they turn to dust (like skeletons) rather than decomposing.

Why aren't other monsters suitable?
Dogs (Lesser Dog, Doggo, etc.): have flesh and biological needs (food, sleep).

Insects (Muffet): although unusual, they obey biological laws (growth, reproduction).

Animals (mice, spiders): do not possess magic and are not connected with SOULS as closely.

The magical nature of monsters
In Undertale, gender is often determined not by biology, but by magic and self-identity:

Ecto-body: Like other monsters, dogs can change shape and appearance. Their gender is not a fixed trait, but rather part of their magical essence.

The soul is more important than the body: the monster's SOUL (inverted and white) has no gender. Gender is merely a shell, not a reflection of its essence.

Identity flexibility: Dogs may feel differently in different situations, but this does not change their behavior.

Ectobiology: Skeletons can create any physical traits (including sexual ones) through magic. This is called an "ecto-body" or "ecto-magic."

Identity flexibility: the skeleton can "call" any gender - male, female, neuter, or no gender at all.

Lack of Biology: Skeletons have no biological sexual characteristics—only bones and a magical aura. Everything else is the result of magical manifestation.

Choice and feeling: the gender of a skeleton depends on how it feels and what image it wants to convey to others.

34.Blue! Sans: Blue's
full characterization! Sans is an alternate version of Sans from Undertale, whose story revolves around depression, isolation, and coping with difficult emotions. Unlike Killer! Sans and Dust! Sans, his tragedy is more internal, psychological.

What's happening in the world of Blue! Sans
World Blue! Sans is not a standalone AU with a unique setting, but rather a reimagining of the canon Dungeon through the lens of Sans' emotional state. Key features of the world:

Atmosphere: muted colors, predominance of blue and gray tones; a feeling of emptiness and loneliness.

Environment: Locations look abandoned even if there are other monsters in them. The ruins seem even darker, Snowdin is cold and inhospitable, and the Falls is quiet and lifeless.

Time: Often depicted as eternal night or twilight, highlighting Sans' depressive state.

What led to the plot of The Story of
Blue! Sans develops due to a combination of factors that gradually destroy the character's psyche:

Papyrus Death: The loss of his brother becomes the first and strongest blow. Sans feels guilty for not being able to protect him (in different versions, due to genocide, accident, or disease).

Loneliness: After the tragedy, Sans distances himself from other monsters. He avoids communication, considering himself "cursed" or "dangerous".

Past Pressure: Sans remembers previous timelines (thanks to Determination or a special ability), and these memories torment him. He sees how the world could have turned out if he had acted differently.

Inability to correct mistakes: attempts to change the situation end in failure. Sans realizes that he cannot return the Papyrus or heal himself.

Social isolation: Other monsters, not understanding his condition, pull away. Even those who want to help (like Undyne or Alphys) don't know how to do it.

Internal conflict: Sans tries to maintain his personality - love of jokes, lazy lifestyle - but it is getting harder and harder for him. His humor became

32.Killer! Sans: In brief
What's going on:

Sans has merged with Chara's soul after many genocidal playthroughs. He has partially lost his personality, retaining only fragments of his former nature.

The world has been plunged into an atmosphere of violence and despair. Sans acts aggressively, but periodically experiences pangs of conscience - especially due to the death of Papyrus.

The environment is gloomy and destroyed, reflecting the inner state of the character.

Key events:

Multiple genocidal playthroughs of Frisk/Enchantment.

A deal with Chara at the end of one of the genocides: he convinces Sans that resistance is pointless.

A gradual fusion of the souls of Sans and Chara.

The murder of Papyrus is a turning point that intensifies the internal conflict.

The development of the four states of Sans's soul - from trying to preserve himself to complete insanity.

33.Dust! Sans: In brief
What's going on:

Sans tries to stop Frisk/Chara's endless genocidal playthroughs at all costs.

Due to his low LV, he cannot defeat a human directly, so he starts killing other monsters to level up.

Over time, the feeling of guilt disappears, only the obsession to stop the person remains.

After killing Papyrus, Sans finally goes insane. He hallucinations in the form of a ghost of his brother, which reminds him of what he has done.

The world turns into a desolate, dusty space – a symbol of extinction and destruction.

Key Events:

Hundreds of genocidal drops that Sans remembers thanks to her newfound determination.

The realization that it is useless to judge a person is too strong.

Deciding to kill monsters for the LV set.

The murder of Papyrus as the last victim to stop the genocide.

Sans' madness: he sees the ghost of Papyrus, loses touch with reality

The world becomes lifeless, covered in dust.

29.SwapSwap
Essence: "double exchange" - the characters have changed not only roles, but also appearance (for example, Sans looks like Papyrus, and vice versa).

What led to the plot: a joke about what would happen if the Underswap exchange became even more radical.

Key features:

visual confusion – it's hard to know who's who;

the characters were partly mixed, partly remained the same;

comic situations due to inconsistency in appearance and behavior;

meta-jokes about fandom and AU in general.

30.DreamDream
: An alternate version of Dreamtale where Dream couldn't contain Nightmer and the world was plunged into a nightmare.

What led to the plot:

Dream lost the fight with Nightmer;

negative emotions consumed the Tree of Feelings;

All the monsters turned into shadows of themselves.

Key features:

The locations look like distorted versions of Dreamtale;

Dream is the last person who remembers what the world was like before;

the player's goal is to restore the Tree by collecting shards of light;

Melancholic atmosphere with elements of horror.

31.Ink! Sans (Inc!Sans)
Essence: the guardian of the multiverse, the artist who maintains the existence of AU. Does not belong to any timeline.

What led to the appearance:arose

as a meta-character embodying the creativity of fandom;

its existence depends on the activity of artists and authors - the more AUs are created, the stronger the Inc;

The goal is to prevent "artblocks" (stagnation in creativity) and save dying universes.

25.Swapfell
The bottom line: A hybrid of Underswap and Underfell - the characters have changed personalities, but the world has become dark and violent.

What led to the plot: a combination of two concepts - the exchange of roles and the increase in aggression due to difficult conditions.

Key traits:

Underswap's "kind" Sans has become a cruel tyrant;

the "evil" Papyrus from Underfell is the only one who tries to preserve kindness;

the color scheme is dark tones with bright contrasts;

conflicts between the old and new personalities of the characters.

26.TemmieTale
Essence: A world where Tammy (Temmie) is the main race, and the rest of the monsters obey them. Everything is exaggeratedly cute and absurd.

What led to the plot: Tammy's popularity in fandom and the desire to create AUs around their unique style of speech and behavior.

Key traits:

Tammys speak their own language ("wot m8", "u dum");

Sans and Papyrus are fans of Tammy, wear their merch;

the economy is based on the trade of "teh-dollars";

A comic tone, a parody of the canon.

27.CoreTale
Essence: The action takes place in the Hotland, which has become a separate world. Monsters evolved under the influence of the energy of the Core.

What led to the plot:

the Core experiment got out of control, changing the physics of the world;

the energy of the Core began to mutate creatures;

Some monsters gained superpowers, but lost their minds.

Key features:

locations - futuristic laboratories and reactors;

Mettaton is the leader of the mutants, trying to stabilize the energy;

Sans and Papyrus are "pure" monsters that resist mutation;

The mechanics of combat are related to temperature and radiation.

28.EchoTale
Essence: A world assembled from the shards of other AUs. The characters are an "echo" of their original versions, with fragments of memory.

What led to the plot: The destruction of several AUs created an anomalous zone where fragments of realities were mixed.

Key features:

characters remember fragments of other timelines;

locations are constantly changing, rebuilding;

the main character is "Echo-Frisk", who tries to put the world together;

The Theme of Identity: What Makes a Being "Real"?

21.HorrorTale (Horrortale 2.0)
The bottom line: The development of the idea of Horrortale is an even darker and more violent universe, where monsters have finally lost their minds.

What led to the plot:

hunger and deprivation reached a critical point;

Queen Undyne introduced cruel laws of survival ("kill or be killed");

Alphys' experiments with determination led to monstrous hybrids.

Key features:

monsters look disfigured, with unnatural proportions;

in the Ruins, instead of spiders, there are giant mutant insects;

Sans and Papyrus are the last to preserve the remnants of humanity.

22.Glitchtale
Essence: An AU crossover based on Errortale, but with an expanded story and new characters. Focus on the fight against Error! Sans and his allies.

What led to the plot:

Error! Sans became even stronger, began to purposefully destroy AU;

new entities have appeared that can resist it (for example, Bete);

The multiverse is on the verge of collapse.

Key features:

epic battles between AU guardians and destroyers;

characters receive "combat forms" with special abilities;

complex chronology with many timelines.

23.StoryShift
The bottom line: all the characters switched roles and classes - Sans became a guardian, Papyrus became a scientist, Undyne became a king, etc.

Key traits:

Sans is a serious and responsible guardian;

Papyrus is a brilliant but absent-minded scientist;

Asgore is a kind but clumsy cook;

Toriel is the leader of the resistance against Undyne's tyranny.

24.FeralTale
Essence: Monsters have returned to a primitive, savage state. Civilization is destroyed, the strongest survive.

What led to the plot:

a catastrophe (possibly caused by an experiment with determination) destroyed a society of monsters;

barriers between locations collapsed, territories mixed;

Instincts prevailed over reason.

Key traits:

monsters behave like predators or herbivores;

Sans and Papyrus are loners who avoid each other

16.MobTale
Essence: The monsters are organized as a mafia clan in the style of "The Godfather". Asgore is a don, Undyne is a consigliere, Sans is a "councilor".

What led to the plot: the desire to transfer the structure of the Royal Guard to a criminal setting, preserving the connections between the characters.

Key features:

mafia hierarchy instead of royal guard;

the shadow economy of the Underground;

conflicts between families (e.g., Great Danes against others).

17.Reapertale
Essence: Sans becomes a Reaper, absorbs human souls and gains divine power.

What led to the plot: Exploring the theme of power through the absorption of souls - what happens if Sans gains the power of Asriel/Enchantment?

Key traits:

Sans seeks out Chara, meets Toriel (Life! Toriel × ReaperSans);

the absorption of souls leads to transformation into a god, but at the cost of health;

a journey through the dimensions, a meeting with Gaster.

18.GZtale (Glozytale)
The bottom line: the opposite of the canon - the characters are unhappy, the relationships are destroyed, motivation is lost.

What led to the plot: the idea of showing the "dark side" of the Dungeon, where dreams do not come true.

Key traits:

Sans and Papyrus hardly communicate;

Undyne is fired from the guards, falls into depression, Alphys tries to support her;

Asgore and Toriel drifted apart.

19.Whytale
The essence: an absurd AU, where everything is related to the question "Why?". Characters are named with the prefix "Why-" (Why! Sans, Whriel, etc.).

What led to the plot: a joke that became the basis for the whole universe - a play on words and ridiculous situations.

Key features:

surreal humor;

Flowey (Wher The Why) tries to kill the protagonist;

the choice between "Why?" and "Why you?" affects the plot.

20.Angeltale
Essence: monsters and humans have angelic features - wings, halos, light magic.

What led to the plot: the desire to create a "light" AU, opposed to Underfell and Dusttale.

Key features:

aesthetics of heaven and light;

magic is based on harmony and forgiveness;

emphasis on redemption and hope.

12.LittleTale
Essence: All characters are depicted as children, retaining the characters of the original, but showing them in a childish way.

What led to the plot: the idea of showing familiar characters in a more innocent, playful way, revealing their relationships through the prism of childhood.

Key traits:

Asgore is embarrassed to confess his feelings for Toriel, reacts aggressively to Sans and Undyne's jokes;

canonical shipping (Undyne/Alphys, etc.) are preserved, but look more naïve;

comical situations due to children's spontaneity.

13.GasterBlaster
Essence: Sans and sometimes Papyrus can transform into huge flying skulls (as in genocide), gaining powerful combat forms.

What led to the plot: a reinterpretation of the mechanics of Sans' attacks in the genocidal passage - the transformation of his "skulls" into full-fledged combat transformations.

Key features:

dramatic transformations with visual effects;

special voice acting and fighting style;

subtype of Baby Blaster - characters are born in the form of "blasters".

14.Gaster! Sans
Essence: the fusion of the mysterious Gaster and Sans into one character with mystical powers.

What led to the plot: fan interest in the WD Gaster character, who almost never appears in canon, and the desire to give him a "second life" through merging with Sans.

Key features:

different interpretations: from the "emotionless demon" to the comical "cat";

control over time/space, manipulation of bones;

He often acts as a keeper of balance or a mysterious mentor.

15.YandereTale
The bottom line: the characters (especially Papyrus) show yandere traits - obsession, aggressive "love", willingness to do anything for the sake of the object of affection.

What led to the plot: the popularity of the yandere archetype in anime culture and the desire to apply it to the good characters of Undertale.

Key traits:

Papyrus curses the timeline, depriving him of soullessness;

distortion of characters: kindness turns into obsession, care turns into control;

Dark aesthetics with horror elements.

8.Dreamtale / Nightmaretale
Essence: two opposite AUs – the world of harmony (Dreamtale) and the world of negativity (Nightmaretale).

What led to the plot:

Dream and Nightmer, twins created after the death of their mother Nim, divided the world into two parts;

Dream maintains harmony, Nightmer is a source of fear and negativity;

their confrontation determines the fate of the AU.

Key traits:

Dreamtale: the world of harmony, villagers, Dream is the guardian;

Nightmaretale: a world of fear, zombie-like creatures, Nightmer is a destroyer;

The balance between them is fragile and can be disturbed.

9.Horrortale
Essence: A dark AU where monsters have gone mad due to hunger, torture and cruelty.

What led to the plot:

living conditions in the Dungeon became unbearable;

Queen Undyne established cruel laws;

Hunger and suffering led to the madness of the monsters.

Key traits:

monsters have gone wild, lost their minds;

an atmosphere of horror and despair;

Survival is the main goal.

10.Outertale
Essence: AU, where the action is transferred to space. The monsters are aliens, and Frisk is an astronaut.

What led to the plot:

a catastrophe or an experiment transported the Dungeon to outer space;

monsters have adapted to new conditions;

Frisk enters this world without understanding what is happening.

Key features:

space technology, alien landscapes;

Sans is the captain of the ship, Papyrus is the engineer;

The plot is related to the exploration of space and the search for a way home.

11.Aftertale
Essence: AU, where Chara takes control of Frisk's body, and Sans tries to stop it. The world after genocide.

What led to the plot:

Frisk has gone through the path of genocide, but Chara takes control;

Sans (in the form of Geno! Sans) becomes an antagonist or tragic defender of order;

Alphys is the head of the Royal Guard, Undyne is the royal scientist (the roles are reversed).

Key features:

gloomy atmosphere after mass destruction;

Ethical dilemmas: Is it possible to "restart" the world at the cost of new victims?

the conflict between Frisk (resisting Chara's influence) and Sans.

5. Inktale (Inkverse)
   Essence: AU, where Ink! Sans maintains the existence of the multiverse and creates new AUs. Counters Error! Sans.

What led to the plot:

there was a need for a guardian of the multiverse;

Ink! Sans uses the canvas as a tool to create and restore AUs;

conflict with Error! Sans became the driving force behind the plot.

Key features:

Ink! Sans — creator, artist, defender of AU;

it can transfer fragments of worlds, restore destroyed universes;

The goal is to preserve the balance of the multiverse.

6.Errortale (Error! Tale)
The bottom line: a world destroyed by Error! Sans, which blurs the boundaries between AUs and distorts realities.

What led to the plot:

Error! Sans, a creature from the Codex, began attacking the multiverse;

its presence causes glitches, distortions, and the disintegration of worlds;

other AUs became targets for his destructive power.

Key features:

Error! Sans - antagonist, destroyer of AU;

worlds are distorted, monsters turn into glitchy entities;

the plot revolves around trying to stop Error! Sans or survive the chaos.

7.XTale (XTale AU)
Essence: An experimental universe created by XGaster to construct an "ideal" world.

What led to the plot:

XGaster, a scientist and manipulator, began creating and modifying monsters;

he uses determination and magic to experiment;

XGaster's goal is to create a universe without flaws.

Key features:

XGaster controls the course of events, rewrites AU codes;

monsters - guinea pigs or tools of his plans;

Asriel (Code I) and other codes are key figures in his experiments.

1.Underfell
Essence: A dark, violent version of Undertale. Monsters live by the principle of "kill or be killed". The color scheme is black and red.

What led to the plot:monsters

became more aggressive due to the harsh living conditions in the Dungeon;

the balance of power has changed: Sans is a henchman of Papyrus, both are passionate about rock music;

The general atmosphere of the world has become more hostile, the laws of survival have become stricter.

Key traits:

Sans and Papyrus wear black and red suits;

Undyne is a ruthless warrior;

Toriel is the cruel ruler of the Ruins.

2.Underswap
Essence: the characters have swapped roles and personalities. The world is friendlier, but with unexpected twists and turns.

What led to the plot:

there was an "exchange" of personalities between key characters;

the motivations and behavior of the monsters have changed, but their connections have remained Key

traits:

Sans is obsessed with the role in the Royal Guard, loves spaghetti, tries to catch Frisk;

Papyrus is a sloth, almost does not participate in business;

The relationships between the characters have become more comical, but sometimes dramatic.

3.Dusttale
Essence: A tragic AU where Frisk chose the path of genocide and exterminated almost all the monsters. Sans is the last survivor to become paranoid.

What led to the plot:

Frisk went down the path of genocide, killing everyone except Sans;

Sans, in an attempt to stop the cycle of killing, killed Papyrus (which he regrets greatly);

Sans is now obsessed with the idea of restarting the world and taking revenge on the man.

Key traits:

Sans is schizophrenic, paranoid, with an unstable psyche;

the world is empty, full of dust and memories;

an atmosphere of despair and hopelessness.

4.Mafiatale
The bottom line: monsters and humans live together, but the world is ruled by the mafia. Undyne, Sans, and Papyrus are mafiosi.

What led to the plot:

society was rebuilt according to the laws of the mafia;

The Royal Guard became the anti-Mafia police;

Power is distributed among criminal groups.

Key traits:

Undyne, Sans, Papyrus are mafia leaders;

Big Dog, Little Dog and others are policemen;

Conflicts between the mafia and the Guardians determine the plot.

Ruins
Description: A tutorial location where the game begins. It consists of purple stone/brick with white columns and stairs. Iron or stone tablets with inscriptions, green vines on the walls, and small moats with wooden bridges are scattered throughout.

Peculiarities:

full of puzzles (with spikes, switches, buttons);
Toriel lives here, along with many spiders and other weak monsters;
Napstablook likes to stay in the Ruins;
at the end of the location is Toriel's house;
You can take part in the "spider bake sale".
Undertale - Ruins(Orchestral Cover) - YouTube
Snowdin
Description: A snowy town with a Christmas atmosphere. Ice and snow are everywhere, and upbeat music plays. A tunnel runs through the town, allowing quick travel between two entrances.

Peculiarities:

inhabited by monsters with thick fur (bears, rabbits), as well as skeletons Sans and Papyrus and dogs from the Royal Guard (Doggo, Lesser Dog, Greater Dog, Dogami and Dogaressa);
includes the Bunny Sisters' Shop and Hotel, Papyrus and Sans's house, a library with a misspelled sign, and Grillby's Pub;
In the Snowdin forest there is a "Mysterious Door" where, under certain conditions, you can encounter the mini-boss Glyde.
Stream Undertale OST Orchestral: Snowdin (15-27) by Kotyonok Listen online for free on SoundCloud
Waterfall
Description: A dark or dimly lit area dominated by blue and black hues. It features waterfalls, swamps with dark water, ponds, and rivers with glowing water. Echo flowers and blue mushrooms are common.

Peculiarities:

The location is home to Undyne, Napstablook, Mad Dummy, and Mettaton before he receives a body;
there is a Gerson store and a Temmy shop;
the tablets tell the story of people and monsters;
At the end of the location, you need to fight Undyne, after defeating her, access to Hotland opens.
Waterfall and Undyne the Pacifist Undertale #6 - YouTube
Hotland
Description: An arid region built on red-orange rock (probably solidified

7. Symbolism and philosophy
   Determination is a metaphor for human will, perseverance and the ability to change the world.

The shape of the heart is a symbol of emotion, compassion, and connection with others.

Red is associated with life, passion, struggle.

The opposition to the white souls of monsters emphasizes the differences:

people: individuality, willpower, the ability to radical change;

Monsters: Collectivity, Magic, Vulnerability to Determination

4.Role in the Undertale
Human-Monster War:

Seven human souls were used to create a barrier that trapped the monsters under Mount Ebott;

The barrier is fueled by monster soul magic, but can be destroyed by seven human souls.

Alphys Experiments:

The scientist extracted resolve from six fallen human souls;

created amalgamates - unstable hybrids that combine the magic of monsters and the determination of humans.

Asriel Dreammurr:

absorbed the soul of Chara, which gave him great power, but led to disaster;

later, after obtaining all the monster souls and six human souls, he became an almost god-like

(Omega Flowey) flower with a soul altered by Chara's determination;

with six human souls, he is able to rewrite the rules of battle and reality.

Endings:

Genocide: gathering souls to strengthen the protagonist, breaking the barrier;

Pacifist: liberation of the souls of monsters and people, peaceful exodus;

Neutral: Partially using souls to achieve objectives (defeating bosses).

5. Interaction with the
   Barrier Creation: The barrier was created using seven human souls.

Channeling: Monster souls feed the barrier with magical energy.

Destruction:

Seven human souls can completely destroy the barrier;

One soul (with enough determination) is able to weaken or break through the barrier temporarily.

6.Special States
Absorption:

Creatures like Asriel or Flowey can absorb human souls, gaining their power;

leads to transformation (Omega Flowey, Asriel after absorbing Chara's soul).

Decay:Upon reaching 0 HP,

the soul is shattered and shattered to pieces (end of the game);

but determination can restore the soul (the battle with Asriel).

Extract Determination:

Alphys extracted the determination to experiment by creating amalgamettes;

The process is dangerous and unstable.

1. Basic Nature and Form
   Appearance: Takes the shape of a heart, usually red in color (but can change color depending on the SOUL mode).

Orientation: directed downwards (unlike monster souls, which are upside down).

Foundation: Consists of Determination, a key force that distinguishes humans from monsters.

Connection with the body: the soul is not the entire essence of a person, but his life essence, "sealed" in the physical body.

2. Key Properties
   of Strength: One human soul is stronger than almost all monster souls combined.

Survival after death: Unlike monster souls, the human soul can be preserved as energy after the death of the body.

Ability to rewrite reality: Determination allows you to ignore or change the rules of the world (e.g., maintain progress, return after death).

Exponential Growth of Power: Each additional human soul gives not a linear, but an exponential amplification.

Recoverability: Determination can be extracted from the soul (as Alphys did to create amalgames).

3.Colors and types of souls (7 colors of the rainbow)
Each soul embodies a certain character trait and gives special abilities in battle:

Red - Determination:

basic soul of the protagonist (Frisk);

allows you to save on save points, return after death;

restores health and soul in the final battle with Asriel.

Orange – Bravery: Gives

the ability to heal or take more damage;

can ignore some attacks in battle.

Yellow – Justice:

allows you to attack upside down (shoot "bullets" upwards);

Enhances combat abilities.

Green - Kindness: Creates

a shield for protection (e.g. from Undyne's spears);

Reduces attack damage.

Blue – Integrity:

obeys the laws of physics (gravity);

can use the environment as cover.

Blue – Patience:

Requires immobility during certain attacks;

allows you to dodge complex patterns if you don't move.

5. Role in key events of the game
   War between humans and monsters:

human souls were used to create a barrier;

Monster souls have become a "battery" to sustain it.

Breakthrough Attempts:

Asriel absorbed Chara's soul, resulting in disaster;

Alphys's experiments with determination created amalgamates.

Endings:

Genocide: monster souls are destroyed, barrier weakens;

Neutral: some souls die, the barrier remains;

Pacifist: Souls are freed from the barrier, monsters come to the surface.

6. Unique cases
   of Floey / Omega Flowey:

flower soul altered by Chara's determination;

combines traits of magic and determination, but is unstable.

Amalgametes:

hybrids created from multiple monster souls + a drop of determination;

Their souls cannot exist stably and disintegrate.

Ghost Napstabluk:

the soul preserved after the death of the body;

exists as pure magical energy with remnants of personality.

Asriel Drimurr:

the only one who temporarily united the soul of a monster and a human;

his transformation into Omega Flowey is an example of a catastrophic fusion

7.Interaction with the
barrier Support: Monster souls feed the barrier with magical energy.

Restriction: The barrier blocks monsters from exiting, but not humans.

Destruction:

Destroying all monster souls will theoretically bring down the barrier;

Gathering 7 human souls allows you to destroy it purposefully.

8. Symbolism and philosophy The
   white soul is a metaphor:

the purity of intentions of most monsters;

vulnerability to the power of determination;

the collective nature of their existence.

The inverted shape is a symbol of:

the "reverse" position of monsters in the world (underground);

their differences from people without initial hostility.

1.Basic Nature of Monster Souls
Composition: Monster souls are made up of magic (as opposed to human souls, which are made up of determination/Determination).

Color: white (as opposed to red human souls).

Shape: inverted relative to human (symbol of differences between species).

Body Connection: Monsters cannot exist without a soul, which supports their magical essence.

Power Limitation: Monster soul magic is weaker than human determination, so humans are stronger in direct confrontation.

2.Properties and functions
Source of magic: the soul powers all the supernatural abilities of monsters (Sans's teleportation, Toriel's fire attacks).

Emotional connection: the soul reflects the inner state of the monster. Strong emotions (anger, fear, love) can temporarily enhance magic.

Collective Field: The souls of monsters are connected to each other on an energetic level. This explains: the

ability to sense the presence of other monsters;

a collective response to global threats (for example, a barrier).

Barrier Dependency: The magical energy of souls fuels the barrier that keeps the monsters under Mount Abbott at bay. The more monsters, the more stable the barrier.

3.Special States and Transformations
Weakening:

prolonged absence of magic;

isolation from other monsters;

emotional shock (for example, the death of a loved one).

Strengthening:

strong collective emotions (fear of people, hope for freedom);

concentration of magic in certain places (Hotland Core).

Distortion:

under the influence of determination (Alphys's experiments with amalgames);

through the absorption of human souls (hypothetical scenario).

Decay: when the body is destroyed,

the soul dissipates as magical energy;

in rare cases, it can persist as a ghost (Napstabluk).

There are no "pure" races: many monsters combine traits (for example, Lesser Dog - dog + fish).

"Race" status: In the lore of the game, the term "race" is almost never used - more often they just say "monsters" or specify the appearance by appearance.

Humans: a separate race; after the war with monsters, they live on the Surface behind the barrier.

SOULS: All monsters are made of magic and are bound to their SOULS (white, inverted relative to human souls).

Skeletons
Traits: Completely devoid of flesh, retain the shape of the skeleton; They have supernatural stamina and magical abilities.

Examples: Sans, Papyrus.

Ghosts
Traits: Disembodied spirits; can become invisible or pass through objects.

Examples: Napstablook, Mad Dummy.

Goat-like (goat monsters)
Traits: Goat or Sheep traits (horns, hooves, fur); often associated with fire or protection magic.

Examples: Toriel, Asgore.

Amphibians (amphibians)
Features: features of frogs, toads or salamanders; are associated with water and swamps.

Examples: Froggit, Vegetoid, Froggits are ordinary monsters of the Ruins.

Fish / Water Monsters
Features: features of fish, octopus, squid; they live in Waterfall.

Examples: Glyde, Undyne, Lesser Dog (partially combines features of a dog and a fish).

Insects/Arachnids
Features: Exoskeleton, multiple limbs, spider or bug features.

Examples: Muffet, her spiders; spiders in Hotland.

7. Canids (dog-like)
   Features: features of dogs, wolves; they often serve in the royal guard.

Examples: Doggo, Lesser Dog, Greater Dog, Dogamy & Dogaressa.

Birds / Birds
Features: feathers, beaks, wings (not always flying).

Examples: Omen, some background monsters in Hotland.

9. Plants / Plant monsters
   Features: features of flowers, mushrooms, vines; are associated with the magic of nature.

Examples: Flowey (originally a flower), some monsters of Waterfall.

Artificial/Mechanical
Features: created by magic or technology; They can be dolls, robots.

Examples: Mettaton (in robot form), some Hotland puzzles (partially animate machines).

11. Hybrids/Amalgamates
    Features: fusion of several species; the result of Alphys's experiments with determination. They cannot exist stably.

Bosses / Unique Monsters
Features: Does not fit into general categories; They have great strength and special abilities.

Examples: Asriel Drimurr, Omega

Underverse background monsters are secondary characters that inhabit various alternate universes (AUs) and create a world atmosphere. Their race and appearance are often tied to the overall AU theme. Let's look at a few examples from different universes.

Underfell
In this AU, monsters have become more violent and aggressive due to the harsh living conditions in the Dungeon. Among the background characters are:

Napstablook is a ghost monster that often appears in background scenes. It retains some melancholy, but in Underfell, its design can be darker.
Monster Kid is a child monster who is occasionally seen in crowds. In Underfell, his image can be more rude or intimidating.

Sad Mew Mew is a sad monster cat that can also appear in background scenes.

The original Undertale

universe Before the Fall of Frisk: Humans and Monsters in a Cold War State. Monsters are trapped under Mount Ebott, people are afraid of them.

After the pacifist path: the dialogue begins, the monsters come to the surface.

After genocide: hatred and fear on both sides, monsters see humans as a threat of annihilation.

XTale (XGaster World)

Formally, humans and monsters coexist, but under the tight control of XGaster.

Reality: Monsters are test subjects in experiments to create a "perfect" universe. Humans are either destroyed or used as a resource (e.g., souls to manipulate the code).

Key example: X!Chara seeks to destroy all AUs, whether humans are a tool or an obstacle.

Underfell

General atmosphere: hostility. Monsters see humans as enemies by default.

Dynamics:

monsters are aggressive, survival of the fittest;

people trapped in the Dungeon are seen as a threat or prey;

Rare alliances are possible only on the basis of strength or advantage.

Underswap

Basic setup: friendlier relations due to "role swapping" and softening of characters.

Examples:

Sans is a kind joker who helps people adapt;

Papyrus is a strict but fair guard, ready to give a chance;

in AU with a completed pacifist, monsters and humans live together.

Dreamtale / Nightmaretale

Dreamtale: harmony. Dream! Sans keeps the world going, monsters and humans help each other.

Nightmaretale: fear and suppression. Nightmare! Sans uses hatred, monsters attack people as a source of negative emotions.

Inkverse

Neutrality: Ink! Sans does not divide creatures into "humans" and "monsters". AU's creativity is important to him.

Practice: He rescues key characters of both species if they are needed to preserve the multiverse.

Error! Tale

Chaos: Error! Sans breaks down boundaries, so relationships are unpredictable.

Trend: Monsters and humans fall victim to his attacks or turn into glitchy entities with no identity.

Personality disintegration is caused by too frequent transitions or a discrepancy between the laws of physics.

Absorption by the Codex - if the creature has no protection (like Error! Sans).

Anchor binding – without a connection to the home world, the traveler loses memory/power.

XGaster/Error Hunt! Sans - They track anomalies in the multiverse.

Energy Hunger - In some AUs (e.g. Nightmaretale), the traveler is exhausted.

Portals and Rifts

Created by XGaster, Ink! Sans, magicians.

Require energy (determination, magic, technology).

They can be stable (gates) or temporary (cracks from attacks).

Code Access

Through direct interaction with the Codex (Error! Sans, XGaster).

Allows you to "rewrite" entry/exit points.

Interdimensional Zones

Journey through the Interworld or the Gravity Pit.

Danger: Risk of dissolving or encountering predatory entities.

Soul

Resonance Characters with similar emotions/goals are attracted to each other through AU.

Example: Frisk can "hear" the call of another person in a parallel world.

Artifacts Amulets of Resolve, Core Crystal Shards, XTale Digital Keys

.

Often disposable or with a limited number of uses.

The Will of Keeper

Ink! Sans or Dream! The Sans can "invite" someone into their world.

XGaster forcibly moves creatures for Chrono Manipulation

experiments

In ChronoTale, movement is possible through time loops.

Risk of paradoxes: Changing the past in one AU can erase others.

5.Mages and technologically advanced creatures

Scientists from XTale - use XGaster machines to create controlled portals.

Dreamtale mages use light spells to transition between worlds with similar energy.

The cyborgs from SynthTale are hacking the digital boundaries of AUs through interfaces.

Limitations: equipment/knowledge required; risk of failure if the laws of physics do not coincide.

6.radial travelers

Anomaly victims are characters pulled into rifts (chronocracks, gravitational pits).

Dreams and projections - consciousness can penetrate into another world in a dream (relevant for Dream! Sans).

Guide Artifacts - Items with multiple AU memories (such as a ChronoTale watch) can carry the wearer.

Limitations: Almost no movement control; high probability of death.

1. Entities with access to the code of the
   XGaster multiverse
   – the creator of XTale, is able to manipulate AU codes, open portals between worlds, and "save" fragments of realities.

Error! Sans - Exists partially in the Codex, can "hack" boundaries between AUs, but distorts worlds when moving.

Ink! Sans - uses his canvas as an interdimensional tool: draws portals, transfers fragments of AU, restores destroyed worlds.

Limitations: Require energy or "anchors" (connections between worlds).

2.Characters with high determination (Determination)

Frisk - thanks to the 1st soul, he can restart timelines, move between paths (Pacifist/Genocide) and, in theory, AU.

Chara - Has a similar power, but uses it to break down the boundaries between worlds.

People with a high level of determination can "break through" to other AUs under extreme conditions (for example, during a genocide).

Limitations: without external help, limited by their timelines; A long stay in someone else's world can cause the disintegration of the soul.

3.Guardians and guardians of the Dream

! Sans - maintains a balance between Dreamtale and Nightmaretale, can stabilize portals.

Nightmare! Sans – penetrates worlds, feeding on negative emotions, distorts the reality around him.

Guardians of AUs (local versions of Sans/Papyrus in different AUs) - Guard the borders of their worlds, but can move to neighboring ones when threatened.

Limitations: tied to their functions; Interference in alien worlds requires permission or extreme necessity.

4. Entities associated with interdimensional zones

The inhabitants of the Interworld are those who survived the destruction of the world and adapted to the void. Can drift between AU shards.

Echo personalities (from EchoTale) are hybrids of fragments of different versions of themselves; instinctively drawn to kindred worlds.

Buggy creatures are organisms that have mutated due to contact with the Codex (for example, versions of monsters from Error! Tale).

Restrictions: do not control the route; often become "slaves" of energy flows between

Willpower/Determination – The higher it is, the more likely you are to get into EchoTale or the Realm of Resolve.

Code Connection – Digital or Buggy Creatures (Error! Sans) are more likely to be included in the Codex.

Guardian Intervention – Ink! Sans or XGaster can "save" someone intentionally.

The nature of the destruction is that a smooth dissolution leads to the Between Worlds, and an explosion leads to the Gravity Pit.

The presence of "anchors" – if there is something related to a creature in another world (a friend, an object), it can attract it there.

Gravity WellWhat

is it: A multiverse black hole that consumes destroyed worlds.

Who gets hit: Most creatures from worlds wiped out without "salvation" (e.g. XGaster victims).

State:

Break down into pure energy;

their power fuels other processes (creating new AUs, strengthening XGaster);

It is extremely rare for someone to break out again.

Example: XTale after the final attack of X!Chara.

Rebirth in a new AU

Scenario: Fragments of the destroyed world are embedded in the structure of the new reality.

How it happens:

people and monsters are reborn as new characters;

can retain partial memory or character traits;

Sometimes they appear as "wanderers" - those who remember the past.

Example: Sans from Underfell can be reborn into Underswap with a changed personality.

Chrono-PocketWhat

it is: Pocket time loops where fragments of worlds get stuck.

Who hits: Creatures destroyed during chrono glitches (e.g. in ChronoTale).

State:

relive the last moments before death over and over again;

can break free if someone breaks the noose.

Example: A world where Toriel is forever falling into the Ruins before reaching the bottom.

The Code / Digital Layer

What is it: The meta-level of reality is the code that governs the existence of AU.

Who hits: Those

whose essence is closely related to the code (e.g., Error! Sans);

characters destroyed as a result of the "failure" of the multiverse.

Status:

Turn into pieces of data;

can persist as algorithms or viruses;

sometimes they are able to influence other worlds from within the code.

Example: Error! Sans exists partially in the Codex, breaking down its structures.

The Guardian World (Inkverse)

What is it: a space created by Ink! Sans to preserve destroyed AUs.

Who hits:the

key characters that Ink! Sans manages to "capture" before the destruction of the world;

important locations saved as artistic images.

Condition:

exist as paintings or sketches;

retain consciousness, but are limited to the canvas;

can be "redrawn" into a new reality.

Example: Ink! Sans sometimes restores AU fragments to give their occupants a second chance.

Echo Realities (Echo #EchoTale)

What they are: Hybrid worlds assembled from the shards of other AUs.

Who hits: any creatures "picked up" by the flow of interdimensional energy.

State:

mixed with fragments of other versions of themselves;

they remember fragments of different lives;

can acquire new abilities or personality distortions.

Example: AU, where Sans is a mixture of classic, Error, and Dream versions.

Determination RealmWhat

it is: A mystical dimension fueled by the power of Determination.

Who hits: those who had a strong determination in destroying the world (humans, some monsters).

State: Become

ghosts of will, entities capable of influencing the fate of the multiverse

can be reborn in a new world with the same goals;

sometimes turn into "anchors" that hold the fragments of their world.

Example: Chara in some AUs gets here after genocide.

The In-BetweenWhat

is it: The empty space between AU is a gray, hazy void.

Who gets in: everyone whose worlds are destroyed: people, monsters, even fragments of locations.

State:

Beings do not disappear all at once, but exist as "echoes" – echoes of memory and energy;

they can retain consciousness, but lose touch with their native reality;

slowly dissolve unless they find a new world or source of power.

Role in the plot: a place of meetings, negotiations, battles between the guardians of the AU.

Example: In the Underverse, shards of XTale and other AUs fall here after XGaster or Error attacks! Sans.

Coffeetale

A cozy world where everything revolves around cafes and friendly meetings.

Sans is a barista, Papyrus is a pastry chef.

There are no conflicts, only warmth, coffee and conversations.

StarTale

A space version of Undertale: the characters are ship captains, explorers of the galaxy.

The dungeon is replaced with a space station.

Aesthetics: neon lights, star cards, spacesuits.

AnimeTale

AU, stylized as anime of the 90s: bright colors, dynamic poses, hypertrophied emotions.

The plot repeats the original, but with the comedic and dramatic clichés of anime.

RoyalTale

An alternate history where Toriel and Asgore do not separate, but rule together.

The royal family is trying to restore relations with people.

Emphasis on diplomacy and politics.

EchoTale

AU, based on the concept of "echoes" – echoes of events stuck in time.

The characters remember fragments of other realities, but do not understand why.

Atmosphere: mystery, déjà vu, distortion of memory.

Summary
These Worlds (AUs) expand the Undertale universe by proposing:

alternate plots (Storyshift, Aftertale);

key change (Horrortale, Dusttale, Coffeetale);

hybrid concepts (Fellswap, Swapfell, HorrorSwap);

MirageTale

Concept: An illusion world where reality is constantly changing and deceiving perception.

Features:

landscapes are rearranged when they are not being looked at;

characters remember different versions of events;

Sans is the only one here who is partially aware of the illusory nature of the world, but cannot control it;

Color palette: pastel colors with sudden bright flashes.

Plot potential: the characters try to find the "true" reality or accept the mirage world as a home.

2. LuminTale

Concept: A universe built on light and shadow – the magic is based on lighting control.

Features:

The dungeon is illuminated by giant crystals that give eternal light;

monsters are divided into "Daylight" (get power from light) and "Night" (stronger in the shadows);

Sans is the guardian of the last crystal that begins to fade

Outertale

A world where the action takes place outside the Dungeon, on the surface.

Humans and monsters coexist openly.

The characters retain recognizable features, but live an ordinary life: Sans works in a café, Papyrus is a policeman, etc.

Fellswap

A hybrid of Underfell and Underswap: an exchange of roles in a dark universe.

Papyrus here is a cruel guard, Sans is a cynical joker with a sarcastic sense of humor.

Color palette: dark tones with bright red accents.

The conflict between the characters is exacerbated by their "inverted" characters.

Storyshift

Another AU with a "role swap", but a more thoughtful development of the plot.

Key changes:

Papyrus is king instead of Asgore;

Sans is a scientist who studies soul magic;

Chara is the leader of the royal guard;

Toriel is a hermit in the Ruins.

The plot develops in a new way, preserving the spirit of the original.

Aftertale

AU, which explores the aftermath of the Undertale (especially the Genocide path).

Frisk and Chara interact on a meta level, trying to "restart" the world.

Sans can act as an observer or referee.

Themes: guilt, redemption, the cyclical nature of time.

Undernot

: A world where all the monsters have died, and the Dungeon is an abandoned ruin.

The only survivor is Sans, who is slowly going mad from loneliness.

Atmosphere: post-apocalypse, melancholy, despair.

He is often depicted with sepia, dust and debris.

Glitchtale

Fan-made AU with a focus on dark magic and the concept of "determination".

Chara becomes the main antagonist, using the power of determination to destroy the boundaries between worlds.

Sans is one of the last defenders here.

Visual style: Gothic, with bright flashes of magic.

Mafiatale

AU, where monsters are organized into mafia clans.

Asgore is the "godfather", Sans and Papyrus are his "soldiers".

The plot is built around intrigues, deals and power struggles.

Stylized as noir and gangster films.

Original UndertaleThe

canon world of Undertale.

The events of the game take place here: people fall into the Dungeon, monsters under the rule of Asgore, Frisk changes the course of history.

In the Underverse, this universe serves as a "reference point".

XTale (X-Tale)

A world created by XGaster, a mysterious creature capable of manipulating AU codes.

Features:

sterile white, almost digital world;

Characters are "versions" of the original monsters with altered personalities and powers.

X!Chara is a key figure, an antagonist who seeks to destroy other universes;

the world exists as an "experiment" or "simulation" under the control of XGaster.

Underfell

A dark, aggressive version of Undertale:

monsters are cruel, humans are enemies;

Sans is a ruthless guard, often depicted with a red eye and scars;

The color palette is dark tones, red, black.

Underswap

"Swapping roles"Characters swap personalities and responsibilities:

Papyrus is serious and strict, Sans is a carefree prankster;

Many heroes gain new abilities and designs;

The atmosphere is lighter, but with dark subtexts.

Horrortale

Horror, horror version of Undertale:

Dungeon in desolation, monsters disfigured or insane;

Sans is one of the symbols of AU: a skeleton with bloody footprints, a frightening smile, and mental instability;

emphasis on fear, survival, psychological trauma.

Dreamtale

A bright, kind universe:

Dream!Sans is a peace-loving keeper of dreams, spreads positivity;

the world is filled with flowers, butterflies, pastel colors;

contrasted with Nightmaretale.

Nightmaretale