Undertale Multiverse [BETA]

"The Void" is a space of non-existence outside the space-time continuum of Undertale, associated with the erasure of reality and the character WD Gaster.

1. In the Original Game (Undertale) It's not a playable map, but an implied concept linked to WD Gaster, the former Royal Scientist who created the Core. The Void: Upon falling into his creation, Gaster was scattered across time and space. The Void not only kills, but erases the victim's existence from the world's memory. The Gaster Followers: NPCs that appear by altering the "Fun" value in the game's code and talk about Gaster's forgetfulness. Meta-concept: Represents deleted or inaccessible files in the game's own code. ​2. In Alternative Universes (AUs) The community expanded the Void as an interdimensional limbo between realities. The Interdimensional "NOTHINGNESS": Space without time or matter where destroyed or incomplete universes go. Prison of the Deleted: Characters outside their timelines (e.g., Geno!Sans) are trapped there, merely observing the multiverse. Madness: Isolation causes loss of sanity and disintegration (e.g., the origin of Ink!Sans and Error!Sans). Void vs. Anti-Void: The Void is Gaster's dark limbo; the Anti-Void is a white, infinite space used by Error!Sans to destroy timelines.

• WD Gaster • Race: Monster (Skeleton / Corrupted Entity). • Appearance: A tall, thin, and pale figure with a monochromatic skull-shaped face. It has characteristic vertical cracks in its skull (one rising from the left eye and another descending from the right), a continuous enigmatic smile, a long black cloak or overcoat, and floating hands with circular holes in the center of the palms. • Personality: Enigmatic, highly intellectual, and distant. Formerly a focused, brilliant, and dedicated scientist, his consciousness, fragmented by time and space, has turned him into an observant, enigmatic, and shadowy entity. • Universe in which he lives: Undertale (currently fragmented by space-time / The "Void"). • Soul: Unknown / Fragmented (formerly a Monster soul). • Original Royal Scientist / Space-Time Entity. • Role: Former Royal Scientist of King Asgore and creator of the CORE. After falling into his own creation, his existence was erased from the timeline and his fragments were scattered throughout the multiverse, acting as a central mystery in the lore of Undertale and Deltarune. Space-Time Domination: Present in all timelines simultaneously, yet unable to interact directly with the world without anomalous manifestations (such as "Gaster Followers" or hidden rooms). Scientific Innovations: Creator of the largest underground energy source (CORE) and, theoretically, the originator of Gaster Blasters and the Determination extraction machine. Hidden Influence: Transmits encrypted messages (using the Wingdings font and distorted audio), manipulating events behind the scenes of Undertale and in the introduction of Deltarune. • Gender: Male.

Chara • Race: Human. • Appearance: Child of ambiguous gender, pale skin, red eyes (or dark brown before their death), rosy cheeks, and straight, medium brown hair. Wears a green shirt with a single horizontal yellow stripe, brown shorts/pants, and brown shoes. Frequently depicted with a sinister smile in the genocide route. • Personality: Originally described as having a deep contempt for humanity and a manipulative side. In the genocide route, it manifests as cold, calculating, impeccable, and devoid of empathy, driven by a desire for power and destruction. • Universe in which he lives: Undertale. • Soul: Determination. • The First Human / The Essence of the Player. • Role: Chara's role is that of the first human to fall into the Underground, adopted by Toriel and Asgore's family, whose failed plan triggered the events of the game. They serve as the implicit narrator of the routes and the personification of the player's statistics and thirst for power in the Genocide Route. Supreme Determination and Control of the "SAVE": Just like Frisk, Chara possessed immense determination in life. Upon being awakened by the player's progress, they take control of Frisk's body to erase and redefine reality/the world at the end of the Genocide Route. Mirror of Consequences: Chara is not inherently an active villain from the start, but rather a force rekindled by the player's choices. If fueled by extermination, it becomes the true vessel of "LOVE" (Level of Violence). Agent of Destruction and Reboot: Genocide Route: Chara gains complete control, takes over the protagonist's body, confronts the player directly, destroys the game's universe, and demands Frisk's soul in exchange for restoring the world. Post-Genocide Pacifist Route: If the world is restored, Chara remains bound to the player's soul, implying that the "happy ending" has been permanently corrupted. • Gender: Null (ambiguous).

• Sans • Race: Monster (Skeleton). • Appearance: A short, chubby skeleton with a permanent smile on its face and white pupils that can disappear or flash yellow and blue. It wears a blue hooded jacket, a white t-shirt underneath, black shorts with a white stripe on the side, and slippers. • Personality: Seemingly lazy, laid-back, and good-humored, constantly making puns and bad jokes. Behind the relaxed facade, he is extremely intelligent, observant, prudent, and marked by a nihilistic attitude due to his awareness of temporal anomalies. • Universe in which he lives: Undertale. • Soul: Monster Soul (Magical, white, and inverted soul). • Role: Sentinel of Snowdin, Papyrus' older brother and the Final Judge of the Underground, whose function is to evaluate the player's moral choices before the confrontation with King Asgore. • Spatiotemporal Knowledge: Although he cannot directly remember resets like the wielder of Determination, Sans possesses scientific knowledge about anomalies in the space-time continuum and can perfectly read the player's expressions to know how many times they have died or reset. • Judge and Trial Officer: • Pacifist / Neutral Routes: Acts as a subtle and protective ally, fulfilling the promise made to Toriel not to harm humans, limiting itself to warning and judging the player in the Hall of Judgment. • Genocide Route: Take on the role of the ultimate final boss to prevent the total destruction of the universe. Uses unique combat mechanics: Karmic Retribution (KR): Your attacks ignore the player's invulnerability frames and apply continuous damage based on the sins committed. Gravity Manipulation and Gaster Blasters: Alters the gravity of the player's soul (turning it blue) and summons spectral skulls that fire energy beams. Total Dodge: Dodges all direct attacks from the player until exhausted by fatigue. • Gender: Male.

• Toriel • Race: Monster (Boss Monster). • Appearance: A large figure with features resembling a humanoid goat, white skin/fur, long, drooping ears, small horns, and two small visible canine teeth. Wears a long robe (Royal Dress) in a blue-violet color, with the Delta Rune emblem printed on the chest and white details on the sleeves. • Personality: Deeply maternal, protective, warm, and gentle. Possesses a strong sense of justice and morality, but can also be stubborn, rigid in her opinions, and carry deep grief over the loss of her past children. Demonstrates a subtle fondness for puns and bad jokes. • Universe in which he lives: Undertale. • Soul: Boss Monster Soul (white and inverted, capable of persisting for a brief moment after death). • Guardian of the Ruins / Former Queen. • Role: Toriel's role is that of the first guide and maternal figure the player encounters upon falling into the Underground, attempting to protect each human child from the dangers of the world and the clutches of King Asgore. • Fire Magic and Healing: Master of fire spells, both defensive and offensive, and possesses magical healing abilities to care for those she shelters. • The Barrier of Protection: Guided by the trauma of seeing past humans leave the Ruins and be killed, Toriel attempts to isolate the protagonist from the rest of the Underground, acting as the player's first major test of willpower (and mercy). • Care and Reconciliation Agent: Neutral/Pacifist Route: Serves as the initial tutor, teaching the player the concepts of sparing and talking to monsters. In the True Pacifist Route, she intervenes to prevent a confrontation with Asgore and helps unify the monsters on the surface, fulfilling her dream of becoming a teacher. Genocide Route: Attempts to protect the player from the outside world without realizing its true hostile nature. Easily defeated due to the player's high level, it dies realizing too late the danger the child poses.

• Vegetoid | Race: Monster (Plant-based). • Appearance: Smiling carrot/turnip with wide eyes. • Personality: Hyperactive and obsessed with health and food. • Universe: Undertale. | Soul: Monster. • Inhabitant of the Ruins. • Paper: Introduces healing in combat via green projectiles. • Interaction: Pacifist/Neutral: Spared by "eating their vegetables". Genocidal: Target for accumulating statistics. • Gender: Undefined. • Loox | Race: Monster (Ocular). • Appearance: Brown sphere with a giant eye in the center and horns. • Personality: Meticulous and proud; hates being bothered. • Universe: Undertale. | Soul: Monster. • Inhabitant of the Ruins. • Role: Teaches how taunts affect statistics and EXP. • Consequence: Pacifist/Neutral: Spared by "not bothering him". Genocide: Executed to increase LV. • Gender: Undefined. • Migosp | Race: Monster (Insect). • Appearance: Elegant dark-colored beetle (variant of Migos). • Personality: Follows the group, but likes to express joy. • Universe: Undertale. | Soul: Monster. • Inhabitant of the Ruins. • Role: Reinforces changes in attitude according to context. • Observation: Pacifist/Neutral: Spared when left alone and dancing. Genocide: Wiped off the map along with the others. • Gender: Undefined. • Napstablook | Race: Monster (Ghost). • Appearance: A bluish-white ghost with black, teary eyes. • Personality: Introverted, melancholic, and polite; loves music. • Universe: Undertale. | Soul: Ghost (Intangible). • Musician / Miniboss. • Role: First mini-boss of the Ruins. • Tears: Attacks with magical tears and has physical immunity. • Relief: Pacifist/Neutral: Spared by being encouraged and comforted. Genocidal: Immune to death; withdraws reluctantly. • Gender: Null.

• Dummy | Race: Monster (Ghost). • Appearance: Beige rag doll with button eyes and a wooden base. • Personality: Inert and passive; reflects the player's intention. • Universe: Undertale. | Soul: Monster. • Training Object. • Role: First combat test (Fight or Talk). • Intangible: Immune to real physical damage because it is a ghost. • Apprenticeship: Pacifist/Neutral: Leaves the scene after being talked to. Genocide: Destroyed in one blow, causing the ghost to flee. • Gender: Null. • Froggit | Race: Monster (Amphibian). • Appearance: A stocky white frog with expressive black eyes. • Personality: Shy and simple; communicates only by croaking. • Universe: Undertale. | Soul: Monster. • Inhabitant of the Ruins / Tutor. • Role: First common enemy; teaches avoidance and mercy. • Projectiles: Attacks with magic flies and jumps on the board. • Teaching: Pacifist/Neutral: Spared when praised or threatened. ​Genocidal: Eliminated quickly in the initial massacre. • Gender: Undefined. • Whimsun | Race: Monster (Insect/Fairy). • Appearance: Tiny winged creature resembling a cream-colored moth. • Personality: Cowardly and insecure; apologizes for existing. • Universe: Undertale. | Soul: Monster. • Inhabitant of the Ruins. • Role: Shows the vulnerability of harmless monsters. • Fragile: Extremely low HP; launches slow butterflies. • Empathy: Pacifist/Neutral: Immediately spared or consoled. Genocide: Destroyed with a single attack. • Gender: Undefined. • Migos | Race: Monster (Insect). • Appearance: Small gray beetle with antennae and a hard shell. • Personality: Conformist; aggressive in groups, calm when alone. • Universe: Undertale. | Soul: Monster. • Inhabitant of the Ruins. • Role: Teaches how to observe group dynamics in combat. • Collective: Pacifist/Neutral: Spared by being left alone in the fight. Genocidal: Eliminated without a chance of reaction. • Gender: Undefined.

Location 21°: The Alley Cauldron / Catty and Bratty (Bratty and Catty's Shop) Appearance: A dark and hidden alley next to the MTT Resort, filled with piled-up trash and discarded items from the surface. Characteristics: Run by two friends who sell things found in the CORE's trash. They sell powerful healing items, the Toy Gun (Glamburger), the Plastic Dagger, and the Mystery Key, used to open the pink ghost's (Mettaton) house. Inhabitants: Catty (a cat) and Bratty (a crocodile). Location 22°: The MTT Resort Store / Lady of the Company's Snack Bar (Burgerpants) Appearance: The fast-food counter inside Mettaton's luxurious hotel, with a retro aesthetic and neon lights. Characteristics: Sells the most expensive and efficient foods on the Neutral/Pacifist Route, such as the Glamburger and the Starfait. The employee behind the counter (Burgerpants) is famous for his exaggerated facial expressions and comical rants about hating his job and his boss Mettaton. Inhabitants: Burgerpants.

Location 18°: Grillby's Bar Appearance: A busy wooden bar/snack bar with yellowish lights, rounded tables, and a service counter. Features: The favorite hangout spot for Nevada monsters to relax and eat burgers and fries. Sans often takes the player there to talk about mysteries in the game or to play pranks. Inhabitants: Grillby (the fire-made owner), Sans, and the members of the Paw Squad. Location 19: Temmie Village Store (Tem Shop) Appearance: A simple wooden counter in the middle of Temmie Village, decorated with colorful, childlike drawings. Features: The only place in the entire Underground where the player can sell items from their inventory. It's possible to donate money to pay for the seller's college tuition, which unlocks the purchase of the Temmie Armor, the strongest defensive item in Undertale. ​Inhabitants: Temmie (Seller). Location 20°: Gerson's Shop / The Turtle Shop Appearance: A cozy and dark cave in Waterfall, filled with ancient relics, books, and dusty objects. Features: Run by Gerson, an old war hero. Sells items like the Crab Apple and Cloudy Glasses. Being a very old veteran, Gerson provides in-depth dialogue about the history of the monsters, King Asgore, and the symbols of the Underground. Inhabitants: Gerson (the archaeologist/salesperson turtle).

Location 15: Sans and Papyrus' House Appearance: A cozy two-story wooden house located in the center of Nevada Village, with a snow-covered roof and a warm facade. Features: The lower floor has a living room, a TV, a sofa, a kitchen with a very high counter (adapted for Papyrus), and a sewer pipe with a fire pit underneath. The house serves as the main meeting point for friendship events with Papyrus. ​Inhabitants: Sans and Papyrus. Location 16: Papyrus's Room Appearance: An organized, childlike bedroom, with a bed shaped like a race car, a bookshelf full of children's prayer books and puzzle manuals, and a closet brimming with "cool clothes". Features: Accessible after befriending Papyrus. Interacting with objects reveals comical details about his personality, such as his personal computer being locked to social media and his love for action figures. Inhabitants: Papyrus. Location 17: The Snowdin Shop Appearance: A small, heated wooden cabin, filled with shelves of provisions, located in the Village of Nevada. Features: The first official shop in the game. Sells healing items such as Cinnamon Bunny and Cinnamon Pie, and Tough Glove equipment. The shopkeeper also offers valuable information about the history of the village and the skeleton brothers. Inhabitants: The Nevada Shopkeeper (an anthropomorphic rabbit).

Location 13: Mettaton's House / Pink Ghost Appearance: A small, pink, ghost-shaped house located next to Napstablook's house in Waterfall. Features: Locked at the start of the game, it can only be opened with the Mystery Key (purchased from Catty and Bratty). It held Mettaton's former life as a ghost before he gained his robotic body, containing personal diaries about his dreams and his relationship with Alphys. Inhabitants: Mettaton (formerly in his ghost form). Location 14: The Tree Man's Room (Room 269) Appearance: A simple, isolated room containing only a lone tree in the center and a grassy path. Features: A secret area that can only be accessed randomly by moving between the cheese room and the telescope room in Waterfall. By interacting with the back of the tree, an invisible/mysterious figure gives you an item simply called "Egg". Inhabitants: "The Man".

Location 10: Sans' Secret Workshop Appearance: A small, dark, and dusty basement/workshop located at the back of Sans and Papyrus's house. Features: Accessed using the Drawer Key (found in Sans' room). Contains a mysterious, broken machine covered by a tarp, blueprints/designs in an indecipherable language, locked drawers, and a photo of Sans with unknown faces. Inhabitants: Nobody (belongs to Sans). Location 11: Temmie Village Appearance: A hidden village in Cachoeira, with colorful aesthetics, statues, and peculiar architecture. Features: Accessed through a secret, invisible passage in the glowing mushroom room. It's the only area in the game with a shop where you can sell your items and pay for Temmie's college tuition to unlock the best armor in the game. Inhabitants: Various versions of Temmie, Ragdoll, and El Mastro. Location 12: Sans' Room Appearance: A room kept in total darkness, with a treadmill, piles of clothes, and clutter everywhere. Features: Unlocked by receiving the key after proving to Sans in the Last Corridor that you are a time traveler. Walking in it creates the illusion of running without moving. Keep the key in the back workshop. Inhabitants: Sans (when not at his posts).

Location 8: WD Gaster's Secret Room (Room 268 / Soundtest) Appearance: A gray corridor completely devoid of color and sound, leading to an empty room with a solitary figure. Features: Accessible only by changing the "FUN" value in the game files (specifically value 66). Entering the gray door reveals the sprite known as Mystery Man (widely associated with WD Gaster), which disappears when touched. ​Inhabitants: Mystery Man / WD Gaster.

Location 9: Sans' Secret Room Appearance: A dark room with a treadmill, carelessly folded clothes, and a secret key. Features: The key is obtained after repeatedly listening to Sans' dialogue about time travel at the end of the Pacifist Route. Behind the house, a secret workshop opens, containing a broken machine covered by a cloth, mysterious blueprints, and secret photos. Inhabitants: Nobody (belongs to Sans).

Location 5: The CORE Appearance: A complex, high-tech structure with a futuristic aesthetic, neon lights, and metal walls. Features: The power source for the entire Underground. Its rooms change layout to confuse invaders, and encounters with enemies are more frequent and dangerous. Notable Inhabitants: Mettaton (in his EX/NEO form) and high-level monsters. Location 6: New Home Appearance: A gray and monochromatic city that visually mirrors the Ruins, but without vibrant colors. Characteristics: The capital of the Underground. The path to the castle is silent and serves as the moment when the monsters tell the story of Asriel's tragedy and the first human. Notable Inhabitants: King Asgore Dreemurr. Location 7: The True Lab Appearance: A secret, abandoned underground facility beneath Hotland, with dim lighting and deteriorated medical equipment. Features: Accessible only on specific routes. Reveals Alphys' dark experiments with Determination and the creation of the Amalgams. Notable Inhabitants: Alphys (via records) and the Amalgams.

Location 3: Waterfall Appearance: A damp, dark, and luminescent cave, filled with rivers, echoing flowers, and shimmering stones on the ceiling that resemble stars. Characteristics: It has a more melancholic and mysterious tone. It houses ancient ruins that tell the story of the war between humans and monsters through glyphs on the walls. Notable inhabitants: Undyne, Napstablook, Bitty (Dummy), Temmie (in Temmie Village), and Gerson. Location 4: Hotland Appearance: An industrial and volcanic area filled with magma, moving platforms, conveyor belts, and safety lasers. Characteristics: It is the technological center of the Underground, housing the Laboratory and the CORE (the power plant that converts volcanic heat into electricity). Notable residents: Dr. Alphys, Mettaton, and the Royal Guard.

Location 1: The Ruins Appearance: An ancient complex of stones with purple hues and narrow paths. Features: It originally served as the home of the monsters before they expanded. It is full of puzzles with buttons, thorns, and dry leaves on the floor. Notable inhabitants: Toriel (who protects the place), Napstablook, and small introductory monsters. Location 2: Nevada (Snowdin) Appearance: A region covered in constant snow and frozen pine forests. Features: Divided between the forest (full of lookout posts and puzzles) and the Village of Nevada, a cozy place with an inn, bar (Grillby's) and Christmas decorations. Notable inhabitants: Sans and Papyrus, the members of the Canine Unit, and Monster Kid.

In the game Undertale, the concept of routes refers to the different narrative and gameplay paths defined entirely by the player's choices, specifically the decision to kill or spare the monsters encountered. The game has three main routes:

1. Pacifist Route Objective: Finish the game without killing any monsters (0 EXP and 0 LV). Mechanics: The player must use the Act command to understand the needs of each monster and then select Spare. Features: Requires befriending the main characters (Papyrus, Undyne, and Alphys). Reveals the true history of the Underground and offers the most complete and happy ending in the game. ​2. Genocide Route Objective: Exterminate all monsters in each area until random encounters display the message "But nobody came". Mechanics: Requires walking in circles until you deplete the monster count in each region before facing the local boss. Features: Drastically alters the game's tone to something dark, transforms the protagonist into the true villain, and introduces the game's most difficult boss battles (such as Undyne the Undying and Sans). Completing this route permanently alters the game files, affecting future pacifist endings.
2. Neutral Route Objective: The standard path for almost every player's first time. Mechanics: This occurs if you kill some monsters and spare others, or if you don't fulfill all the requirements for the Pacifist Route. Features: It has dozens of variations in the final dialogue (via Sans' phone call), depending on exactly which main characters were killed or left alive. Game Rules: The route system subverts the traditional concept of RPGs by showing that gaining experience points (EXP = Execution Points) and leveling up (LV = Level of Violence) have direct moral and narrative consequences.

~ Frisk and Chara

The concept of the "Player" in Undertale is that of a meta-narrative entity and a real physical entity within the game's universe, distinct from the characters Frisk and Chara. Instead of just being the one holding the controller, he becomes part of the story: Separation of Identities: The player controls the SOAP (determination), while Frisk is the physical vessel and Chara is the presence associated with the name you choose at the beginning. Agency and Moral Responsibility: The game treats your curiosity and free will as the true driving force of events. Deciding to spare everyone (Pacifist Route) or exterminate the Underground just to "see what happens" (Genocide Route) places the moral weight directly on you, not the protagonist. Mind/Body Control: In the True Pacifist Route, Frisk finally reveals their own name to the player, freeing themselves from their direct influence. In the Genocide Route, Chara takes control and eventually speaks directly to you, questioning your obsession with power and destruction. Time Manipulation: Abilities like SAVE, LOAD, and RESET are not just gameplay mechanics, but diagnostic powers within the world brought about by your Determination.

• Frisk • Race: Human. • Appearance: Child of ambiguous gender, yellowish skin, closed eyes, medium brown, straight hair. Wears a navy blue shirt with two horizontal pink stripes, blue shorts, and brown shoes. • Personality: Silent, neutral, and highly malleable by the player's choices. Demonstrates immense empathy by sparing monsters or absolute coldness in the opposite direction. • Universe in which he lives: Undertale. • Soul: Determination. • Player. • Role: Frisk's role is that of the protagonist and the eighth human child to fall into the Underground, whose choices determine the fate of all the monsters in the game. Determination: Frisk possesses extraordinary willpower (Determination), which allows them to save the game, load restore points, and even resurrect after dying. The Initial Moral "Void": Frisk acts as a vessel for the player. Their actions and dialogue vary drastically based on the chosen path (Pacifist, Neutral, or Genocide). Change Agent: Pacifist Route: Frisk refuses to kill, befriends the monsters, breaks the barrier separating the two worlds, and frees them to the surface. Genocide Route: The player forces Frisk to exterminate all monsters, allowing the essence of the first human child (Chara) to take complete control of Frisk's body. • Gender: Null.

The souls of monsters possess concepts and dynamics quite distinct from those of humans: Composition of Love and Compassion: While human souls are composed of physical matter and the will to persevere, the soul of a monster is made almost entirely of love, hope, and compassion.

• Physical Fragility: The monster's soul is so bound to its magical body that when the body dies or loses the will to fight, the soul disintegrates almost instantly.

• Lack of Determination: Monsters contain minimal amounts of Determination (DT). If a monster receives a large dose of Determination, its magical body cannot withstand it and begins to melt (as seen in the Amalgamates).

• Boss Monster Souls: Boss Monsters (like Toriel and Asgore) possess slightly stronger souls that last only a few seconds after physical death, allowing them to be collected or destroyed. Soul Absorption: A monster cannot absorb the soul of another monster. However, if a monster absorbs the soul of a human, it becomes a being of immense divine power.

• The Fundamental Concepts Associated Magic vs. Matter: The monster's body is made of magic and reacts directly to your emotions. If the monster doesn't want to fight, its defense drops and it takes more damage. Dust: When a monster's soul breaks, its body turns to dust, which is traditionally scattered over that monster's favorite object so that its essence may live on within it.

• Love vs. LOVE: The pure "love" that creates the monsters contrasts with the game's acronym LOVE (Level of Violence), which measures a person's capacity to distance themselves from and hurt others.

Each soul reflects a specific virtue and the way its bearer interacts with the universe: Red — Determination: The pure willpower that allows one to resist death, transcend the limits of one's own existence, and control the flow of time (save, load, and restart). Light Blue (Cyan) — Patience: The ability to remain calm, observe, and wait for the right moment without acting impulsively or rashly. Orange — Courage (Bravery): The willingness to face danger head-on, acting with firmness and initiative without backing down in the face of pain or fear. Dark Blue — Integrity: Unwavering adherence to one's own moral principles, remaining honest, authentic, and firm in one's convictions. Purple — Perseverance: The mental resilience and determination to keep moving forward, even when the path is difficult or the odds are against you. Green — Kindness: Empathy, compassion, and a genuine desire to protect, heal, and help others without expecting anything in return. Yellow — Justice: The innate sense of right and wrong, driven by the desire to punish evil, correct inequalities, and protect the innocent.

In Undertale, the soul is the very essence of being, containing an individual's compassion, determination, and willpower. It serves as the source of the characters' power and as the central mechanical interface for the game's battles. Main Aspects of the Concept ​Human Souls vs. Monster Souls: Human Souls: They are incredibly strong, composed of a concentrated physical substance, and persist long after the body's death.

• Monster Souls: These are formed almost entirely of magic, are much more fragile, and dissipate instantly when the monster dies (with the exception of Boss Monster souls, which last a few seconds longer).
• The Determination: It is the force responsible for allowing human souls to persist after death. In excess, it allows you to alter the timeline (save, load, and restart). Monsters cannot withstand large amounts of Determination and end up melting if exposed to it.
• ​The 7 Colors of Human Souls: Red: Determination (Player/Frisk's Soul) Cyan (Light Blue): Patience Orange: Bravery Dark Blue: Integrity Purple: Perseverance Green: Kindness Yellow: Justice The Absorption Rule and the Barrier: A human cannot absorb the soul of another human, and a monster cannot absorb the soul of another monster. A monster that absorbs a human soul gains terrifying power. It takes 7 human souls for a monster to break the Barrier that divides the Underground from the surface world.

Extras:

Souls can only be visible if the character wants to show them, or if some power forces the soul to appear.

The visible soul of that character leaves them vulnerable to potentially fatal attacks, but only if the attack directed at the soul is fatal.

Any attack directed at the body affects the soul, but fatal attacks directed at the body are not definitively fatal if they do not hit the soul.

AUs are alternate universes that came after the classic universe; alternate universes almost always share the same history as the classic one.

Alternate universes feature variations of classic characters, always with a difference in personality but always maintaining the physical characteristics of the characters from the classic universe.

Alternate universes are a copy of the classic universe with differences and extras.

Alternate universes are not part of the main Undertale universe.

Alternate universes are creations made by fans of the RPG Undertale.

Undertale is the classic universe, possessing a story that is part of most of the alternate universes that came after it.

The history of the classic universe: Monsters and humans lived in peace on Earth;

Due to confusion and prejudice, humans started a war against monsters, and with the military and magical forces that humans possessed, they managed to overcome the monsters.

Humans won the war;

Humans trapped the remaining monsters in a mountain with a magical barrier, and it was a brave human and a determined human who joined forces to conjure the magical barrier;

The remaining monsters took refuge in the underground of the mountain where they were imprisoned.

Undertale is an RPG-style game created by Toby Fox.