The Undertale fan community has birthed a multiverse of alternate universes (AUs) that reinterpret, expand, or completely reimagine the original game's characters, lore, and themes. In order to organize these countless creations, we have devised a hierarchical classification system. This system not only categorizes each AU by its core thematic elements but also provides a framework to assign unique identification numbers. Each category is designated by a "hundred" number (i.e., "100", "200", etc.) that signifies a broad thematic grouping. Sub-categories further refine these groups, with each group containing multiple unique identifiers.
This guide is divided into several main categories:
"100" – Classic & Original Undertale AUs (Foundation Tier)
"200" – Darker, Angrier, or Twisted Variations
"300" – Role-Swap, Playful, or Reimagined Variations
"400" – AUs Defined by Decay, Erosion, or Fading Existence
"500" – Horror, Gloom, and Unsettling Reimaginings
"600" – Experimental, Radical, and Unorthodox Creations
"700" – The Underverse & Multiversal Originals
"800" – Special, Omega Tier, and Legacy AUs
"900" – Undefined, Aesthetic-Based, and Unique Interpretations
Each primary category contains sub-categories identified by two-digit numbers within that hundred block. For example, in the "100" category for Classic AUs, sub-categories such as 101, 102, 103, 104 are used. Below, we break down each category in detail.
────────────────────── "100" – Classic & Original Undertale AUs (Foundation Tier)
These AUs remain closest to the original Undertale lore, tone, and mechanics. They maintain the core story structure with only minimal alterations, preserving the emotional resonance and familiar conflicts. This foundation is critical because it forms the basis from which many other AUs diverge.
101 – Classic AUs
Definition: AUs in this group include those that present the original Undertale narrative with slight variations. They might adjust character traits or plot details without altering the overarching structure of the story.
Examples:
Undertale itself, where the primary narrative remains largely intact.
Underfell, which adds a darker tone but still uses many of the original character interactions.
Underswap, where roles are exchanged in a playful, sometimes ironic manner.
Context: These AUs are revered for preserving the essential spirit of the original game while exploring "what if" scenarios that tweak key elements. They provide a point of reference for more radical reinterpretations later in the classification system.
102 – Classic Gameplay-Inspired AUs
Definition: These AUs are inspired by specific gameplay experiences or modes. They might explore alternate outcomes based on player choices or enhance existing routes like the Genocide route in ways that accentuate gameplay mechanics.
Examples:
Hard Mode variations that challenge players with increased difficulty without altering the fundamental narrative.
Genocide Route Expanded, where the consequences of extreme choices are deepened and elaborated.
Context: Such AUs often arise from discussions among the community where players wish to experience the game in a different light—by emphasizing the mechanical challenges and the emotional toll of gameplay choices.
103 – Classic-Style AU Expansions
Definition: This sub-category includes AUs that expand the original story by adding new chapters, prequels, or sequels. They explore additional backstories, hidden layers, or alternate endings that build upon the classic foundation.
Examples:
Last Breath, which might serve as a narrative sequel to the original story.
Dusttale, an AU that integrates themes of decay and the passage of time while retaining classic character dynamics.
Disbelief Papyrus, a reinterpretation focusing on Papyrus's personal journey in a subtly altered world.
Context: These expansions are appreciated for their creativity, as they allow fans to dive deeper into the lore while remaining faithful to the established universe.
104 – Non-Altering Retellings
Definition: Retellings that do not significantly alter the core themes or mechanics of the original story. They provide alternate perspectives or reimaginings that maintain the fundamental narrative.
Examples:
Remixes of the base Undertale story that might focus on different character viewpoints without changing the essential events.
Context: These AUs are typically less controversial, as they offer new interpretations while preserving the beloved aspects of the original game.
──────────────────────────── "200" – Darker, Angrier, or Twisted Variations
This category encompasses AUs that emphasize a darker tone. The original optimism or neutrality is replaced by themes of corruption, aggression, trauma, or psychological breakdown. The emotional palette here is more intense and often controversial.
201 – Aggressive & Warped Versions
Definition: AUs that depict a more violent, aggressive world where the characters are hardened by a harsh reality.
Examples:
Underfell, where the world is more hostile, and characters exhibit rougher, more cynical traits.
Dissonant Undertale, which amplifies the more aggressive elements of the original story.
Context: These universes challenge the viewer by presenting what happens when determination gives way to uncontrolled aggression and bitterness.
202 – Corruption-Based AUs
Definition: Universes where corruption infiltrates the hearts of characters. Even once-noble souls become tainted by the dark forces of their environment.
Examples:
Nightmare-Touched AUs, where the pervasive influence of nightmares warps morality.
Abysstale, a universe where the darkness of the Abyss alters the characters beyond recognition.
Context: The concept of corruption in these AUs serves as a commentary on the fragility of morality and how external forces can erode even the purest ideals.
203 – Trauma & Madness-Based AUs
Definition: AUs that focus on the psychological toll of trauma and the descent into madness. The harsh realities of their worlds push characters to the brink of insanity.
Examples:
HorrorSwap, where the swap between characters also involves a descent into psychological horror.
FallenFell, which highlights the devastating impact of trauma on once-hopeful characters.
Context: These narratives are often dark and challenging, intended for an audience that appreciates the exploration of mental and emotional breakdowns.
204 – Void-Linked Darkness AUs
Definition: AUs where the influence of the Void—a mysterious, often corrupting force—intertwines with the narrative, leading to an atmosphere of pervasive darkness.
Examples:
Seraphin-Tier AUs, which tap into void distortions to create a unique blend of beauty and horror.
Context: The Void, as an existential concept, provides a rich backdrop for exploring how darkness can shape and warp reality, affecting even the most resilient souls.
205 – Psychological Breakdown AUs
Definition: Universes that depict the disintegration of mental stability as the characters are overwhelmed by their circumstances.
Examples:
InsanityTale, where the progression of events drives characters into complete psychological collapse.
KillerTale, which examines how extreme stress and loss lead to a breakdown in empathy and self-control.
Context: In these AUs, the narrative focuses on how the mind shatters under relentless pressure, challenging the audience to confront the darkest parts of the human psyche.
────────────────────────── "300" – Role-Swap, Playful, or Reimagined Variations
These universes take a lighter approach by swapping roles, reassigning character traits, or reimagining the narrative in ways that are humorous, unexpected, or meta in nature. They often provide fresh perspectives without diving into dark or aggressive territory.
301 – Direct Role-Swaps
Definition: AUs where characters trade roles entirely, with the narrative structure remaining similar but with flipped responsibilities and dynamics.
Examples:
Underswap, where key characters assume each other's roles in both personality and narrative function.
Storyshift, which reassigns traditional roles to create new interactions.
Context: Role-swaps are often celebrated for their playful subversion of expectations, allowing fans to see their favorite characters in entirely new lights.
302 – Hybrid Swap-Shift AUs
Definition: These AUs mix role-swapping with elements of transformation, where characters not only swap roles but also undergo changes in personality or physical traits.
Examples:
Storyswap, which combines role reversal with narrative twists.
Storyfell, where darker elements are mixed into the role-swapped framework.
Context: The hybrid nature of these AUs adds layers of complexity, often resulting in surprising plot developments that challenge established character dynamics.
303 – Meta-Swaps (Breaking Established Roles)
Definition: AUs that completely break away from traditional roles, where established character archetypes are deconstructed and reassembled in unexpected ways.
Examples:
Swap!Dust, which uses the concept of dust and decay as metaphors for shattered roles.
InkSwap, which redefines character boundaries in a world driven by creative chaos.
Context: These meta-swap AUs invite audiences to question the very nature of identity and narrative structure, often employing a self-aware, sometimes ironic tone.
304 – Comedic or Light-Hearted Reimaginings
Definition: Universes that inject humor and light-heartedness into the reinterpretation of the original story.
Examples:
UnderRacer, a playful take where the Underground becomes a competitive, fast-paced racing world.
Outertale, which situates characters in a cosmic, whimsical setting.
HelpTale, which emphasizes kindness and community through humorous scenarios.
Context: These AUs aim to entertain while still offering fresh perspectives on well-known characters and situations.
────────────────────── "400" – AUs Defined by Decay, Erosion, or Fading Existence
These AUs focus on the theme of decay—where the passage of time, violence, or neglect causes the fabric of reality and the essence of the characters to deteriorate. They often evoke feelings of melancholy, loss, and inevitability.
401 – Decay-Driven AUs
Definition: AUs in this group explore themes of gradual decay and disintegration. The narrative often revolves around the consequences of prolonged violence or neglect.
Examples:
Dusttale, where relentless conflict leaves the world in a state of dust and ruin.
HyperDust, which amplifies the concept of decay to the extreme.
DustDust, an AU in which every element is corroded by time.
Context: These universes serve as poignant reminders of the impermanence of all things and the cost of unchecked destruction.
402 – Annihilation & Reset-Based AUs
Definition: These AUs are defined by the concept of resetting or annihilation. History is repeatedly erased and rewritten as a result of catastrophic events.
Examples:
Last Breath, where the very act of dying resets the world.
Experimental Number Eighteen, an AU that explores the theme of forced rebirth through systematic annihilation.
Context: In these universes, existence is a cycle of destruction and rebirth, with the decay serving as a precursor to a new beginning—if one can survive it.
403 – Glitched or Failing Timelines
Definition: Universes where the timeline itself is unstable—plagued by glitches, errors, and anomalies that cause reality to falter.
Examples:
Errorswap, where timelines frequently malfunction.
Fragmentale, which portrays a world broken into disjointed fragments.
Context: These AUs evoke the chaos of a world where continuity is lost, leading to a fragmented, often disorienting experience for both characters and audiences.
404 – Glitch Entities & Digital Erosion AUs
Definition: These universes focus on digital decay and corruption. The environment and characters suffer from systemic glitches that erode the fabric of reality in a manner reminiscent of computer errors.
Examples:
Error 404, a representation of a timeline where data and reality collapse.
Corrupttale, where the digital and physical worlds become indistinguishable in their decay.
Context: In these narratives, the boundary between technology and magic blurs, leading to unsettling visuals and a sense of impending collapse.
405 – Lost & Forgotten Timelines
Definition: Universes that have been abandoned or erased, where history is lost and the remnants of the past exist only as memories.
Examples:
LostTale, an AU where entire timelines vanish without trace.
ForgottenTale, where the deeds of once-great souls are consigned to oblivion.
Context: These AUs carry a profound sense of melancholy, exploring themes of memory, regret, and the passage of time.
────────────────────────── "500" – Horror, Gloom, and Unsettling Reimaginings
In the 500-Series, the tone shifts drastically. These universes transform the Undertale setting into something eerie, grotesque, or downright terrifying. Here, fear, gloom, and horror replace the lighter aspects of the original narrative.
501 – Horrortale & Horror-Adjacent AUs
Definition: AUs that reimagine the world as a place of horror, where the familiar becomes nightmarish.
Examples:
Horrortale, which is perhaps the quintessential horror AU where everything is dark and foreboding.
Horrorfell, a variant with even more brutal, aggressive tones.
Horrorswap, where role-swapping occurs in a terror-infused environment.
Context: These universes are designed to evoke a visceral sense of dread and challenge the audience's comfort with the original story.
502 – Dark Fantasy Horror AUs
Definition: These AUs blend dark fantasy elements with horror, creating a narrative rich in mythic terror and supernatural dread.
Examples:
TerrorTale, where ancient evils resurface.
AbyssTale, in which the characters confront otherworldly horrors that defy logic.
Context: This subcategory often features elaborate, atmospheric world-building that emphasizes both beauty and horror.
503 – Eldritch Horror & Cosmic Fear AUs
Definition: Here, the focus is on cosmic horror—entities and phenomena that challenge the boundaries of sanity.
Examples:
LovecraftTale, inspired by the works of H.P. Lovecraft.
NightmareTale, where the very fabric of reality seems to be under siege by eldritch forces.
Context: These universes are meant to instill a deep, existential dread, where characters are insignificant in the face of cosmic indifference.
504 – Flesh Horror & Body Mutation AUs
Definition: AUs in this group explore physical horror and grotesque transformations.
Examples:
Experiment-Tale, where uncontrolled experiments result in horrific mutations.
SCP-Tale, which draws inspiration from the SCP Foundation's unsettling lore.
Context: The focus here is on the visceral, often disturbing changes that occur when nature is defied, making for a truly unsettling experience.
505 – Survival Horror & Grim Reimaginings
Definition: In these universes, the struggle for survival is paramount. Every day is a battle, and the horrors of the world are unrelenting.
Examples:
Reapertale, where survival is pitted against an oppressive force that reaps lives without mercy.
ZombieTale, a scenario where infection and decay run rampant.
Context: These AUs often portray a world where the hope for salvation is slim, and every choice can mean life or death.
──────────────────────────── "600" – Experimental, Radical, and Unorthodox Creations
The 600-Series is reserved for AUs that completely defy conventional storytelling. These universes often incorporate new mechanics, entirely different worlds, or radical thematic shifts that push the boundaries of the Undertale narrative.
601 – Abstract Concept AUs
Definition: These AUs are built around abstract, often non-linear concepts.
Examples:
DoodleTale, where the entire world is rendered in a childlike, hand-drawn style.
PaintTale, which transforms the narrative into a flowing canvas of colors and brushstrokes.
Context: The focus here is on creativity and the idea that storytelling can be as fluid and variable as art itself.
602 – Time & Dimensional Travel AUs
Definition: Universes where the central theme revolves around shifting timelines and interdimensional travel.
Examples:
TimelapseTale, which explores the effects of time moving unpredictably.
DimensionTale, where characters leap between vastly different realities.
Context: These AUs often challenge traditional narrative structures by introducing elements of time distortion and spatial discontinuity.
603 – Scientific Experimentation AUs
Definition: AUs that emerge from radical scientific experiments or the application of advanced technology to the original lore.
Examples:
Handplates, which reinterprets the origin of characters through the lens of experimental science.
Core!Frisk, where the human soul is dissected, studied, and reassembled in unexpected ways.
Context: This category highlights the interplay between science and magic, offering a narrative where experimentation leads to both breakthroughs and horrifying consequences.
604 – Reality-Warping or Multiversal War AUs
Definition: These universes involve large-scale conflicts that affect not just one timeline but the entire multiverse.
Examples:
OmegaTale, where battles are fought on a cosmic scale, reshaping reality.
AnomalyTale, in which disruptions in the fabric of existence lead to multiversal warfare.
Context: In these AUs, the stakes are nothing less than the fate of all existence, and characters must confront the very nature of reality.
605 – Meta-Commentary & Self-Aware AUs
Definition: AUs that break the fourth wall, offering commentary on the nature of the Undertale universe and its fandom.
Examples:
FourthWallTale, where characters become aware of their own fictional nature.
ParadoxTale, which plays with narrative contradictions and self-referential humor.
Context: These AUs are often playful, challenging fans to think critically about the nature of storytelling and their relationship with the game.
606 – Genre-Merging AUs
Definition: Universes that combine elements from multiple genres to create something entirely new.
Examples:
Sci-Fi Undertale, which infuses futuristic technology into the familiar setting.
CyberTale, blending cyberpunk aesthetics with the Undertale world.
MedievalTale, where chivalry and knighthood reshape the Underground.
Context: This category celebrates the limitless creativity of fans by merging disparate themes, resulting in rich, multifaceted narratives.
──────────────────────────── "700" – The Underverse & Multiversal Originals
The 700-Series is reserved for AUs and entities that exist beyond the confines of a single timeline. These are creations that transcend conventional AU boundaries and are often seen as the living embodiment of the multiverse itself.
701 – Entities from Beyond Singular Timelines
Definition: Characters in this subcategory are not tied to one specific timeline but exist across multiple realities.
Examples:
Ink!Sans, a figure who embodies creativity and the fluidity of narrative.
Error!Sans, whose existence is defined by glitches and multiversal anomalies.
Cross!Sans, representing a fusion of various influences from multiple AUs.
Context: These entities are often central to the mythos of the Underverse, symbolizing the interconnectedness of all timelines.
702 – Underverse-Dominant Timelines
Definition: AUs that are considered canonical within the Underverse—the multiversal hub where traditional timelines converge.
Examples:
Underverse Canon AUs, which serve as reference points for the broader multiversal narrative.
Context: These timelines act as anchors, providing a consistent backdrop for the chaotic flux of the multiverse.
703 – Multiversal Warriors & Entities
Definition: This subcategory includes heroes, villains, and beings who are instrumental in large-scale conflicts that span across universes.
Examples:
Characters such as Dream and Nightmare, who embody the struggle between hope and despair on a cosmic scale.
Fatal_Error, representing the destructive potential of multiversal collapse.
Context: The actions of these beings often have repercussions that ripple across countless timelines, making them key players in the fate of the multiverse.
704 – Anti-Void and Digital Constructs
Definition: AUs that focus on digital anomalies, anti-void entities, or characters that exist as constructs rather than living beings.
Examples:
Error 404, a manifestation of digital decay and system failure.
Alpha!Sans, a character who represents the inception of digital existence in the multiverse.
Context: These AUs blur the line between reality and technology, emphasizing the fragile nature of digital constructs in a chaotic multiverse.
705 – Beyond-Timeline Watchers & Architects
Definition: Entities in this subcategory oversee or influence the flow of time itself.
Examples:
The Star Sanses, a collective of beings whose purpose is to maintain balance across timelines.
Omniscient Entities, who observe and sometimes manipulate events from behind the scenes.
Context: Their role is often ambiguous—acting as both guardians and manipulators of the multiverse's fate.
──────────────────────────── "800" – Special, Omega Tier, and Legacy AUs
The 800-Series encompasses AUs and characters that have become narrative touchstones—deities, mythic figures, or higher-tier anomalies that define the overall lore. These universes often have a transcendent quality, influencing not only their own timelines but also the broader fan and multiversal narrative.
801 – Omnipotent & Mythological Characters
Definition: AUs in this subcategory feature characters with godlike powers or mythological status.
Examples:
GodVerse Sans, a being whose authority is absolute and whose actions shape entire universes.
Seraphim Sans, who embodies divine qualities and commands respect across the multiverse.
Context: Such characters are rare and are often central to the legends that underpin the entire Undertale multiverse.
802 – Omega-Class Antagonists & Destroyers
Definition: These AUs focus on villains or destructive forces that challenge the very fabric of reality.
Examples:
X-Tale!Chara, an iteration of Chara whose ambition and malice transcend conventional limits.
Omega Gaster, a version of Gaster that represents the end of all things.
Context:In these narratives, antagonists are not just obstacles—they are existential threats that force heroes to rise to extraordinary challenges.
803 – End-of-Timeline Survivors & Multiversal Anomalies
Definition: This subcategory includes those who have survived the collapse of timelines or whose existence is a testament to the multiverse's resilience.
Examples:
UltSans, the architect of the Void and a living legend whose actions preserve the balance of all timelines.
True Horror Entities, who exist as living remnants of the multiverse's darkest moments.
Context: Their survival and influence shape the legacy of the multiverse, making them both revered and feared.
804 – Absolute Reality Distorters & Unbound Entities
Definition: AUs that introduce beings capable of altering reality without constraint.
Examples:
Akumu, a force that distorts the laws of physics and magic alike.
Absolute Ink, whose power lies in rewriting existence as if it were mere script.
Context: These entities represent the ultimate expression of creative chaos—a reminder that in the multiverse, even reality is malleable.
805 – Legacy AUs That Influenced the Fandom's Growth
Definition: This subcategory honors the AUs that have become cornerstones of the Undertale fan community, shaping its evolution over the years.
Examples:
X-Tale, Underverse, Handplates
Context: Their influence is so profound that they are considered integral to the collective memory of the fandom, often serving as benchmarks for quality and creativity.
806 – Canonical Story-Altering Events
Definition: AUs that revolve around pivotal events which dramatically alter the narrative landscape of the Undertale multiverse.
Examples:
The Doodle Sphere's Fall, The Void Wars
Context: These events are considered turning points that redefine the nature of reality and the destiny of all involved.
─────────────────── "900" – Undefined, Aesthetic-Based, and Unique Interpretations
The 900-Series is reserved for AUs that prioritize visual, tonal, or cultural shifts without necessarily altering the core mechanics of the original game. They are often defined by their artistic style, mood, or cultural reinterpretation rather than by changes in the narrative structure.
901 – Visual & Artistic Reinterpretations
Definition: AUs that transform the Undertale world through a distinct artistic lens.
Examples:
Black & WhiteTale, CinematicTale
Context: These AUs celebrate the power of visual storytelling, with changes that may include dramatic shifts in color palette, art style, and atmospheric design.
902 – Minimalist or Symbolic Reimaginings
Definition: Universes where the narrative is stripped down to its core symbolic elements.
Examples:
ShadowTale, NegativeTale
Context: Here, every element is imbued with symbolic meaning, often resulting in a stark, introspective atmosphere.
903 – Music & Performance-Themed AUs
Definition: AUs that center around musical or theatrical reinterpretations of the Undertale narrative.
Examples:
OrchestraTale, RaveTale
Context: These universes emphasize rhythm, performance, and the emotional power of music, often incorporating original scores or live performance elements into their storytelling.
904 – Cultural & Folk-Based AUs
Definition: Universes that reimagine the Undertale story through the lens of different cultures or folk traditions.
Examples:
SamuraiTale, NorseTale, EgyptianTale
Context: These AUs offer a rich tapestry of cultural influences, blending traditional mythology and folklore with the established Undertale universe.
905 – Technological & Digital Variations
Definition: AUs where technology plays a central role in reshaping the world, often with a futuristic or cyberpunk twist.
Examples:
CyberTale, VR-Tale
Context: The narrative here fuses digital aesthetics with classic themes, resulting in a world that is both advanced and nostalgically familiar.
906 – Alternate Physics & Gameplay Styles
Definition: Universes that experiment with different gameplay mechanics or underlying physical laws.
Examples:
FPS-Tale, StrategyTale
Context: These AUs reimagine the game mechanics themselves, offering new challenges and perspectives by altering how the game is played.
How to Use This Classification System
Each primary category is defined by a specific hundred-range (100, 200, 300, etc.), with sub-categories distinguished by their last two digits. For example, an AU classified as "101" in the 100-series would fall under Classic AUs, while one labeled "202" in the 200-series would be a corruption-based AU. This system is designed to be scalable and flexible, allowing you to assign a unique Personal Channel Code (a separate six-digit number) to individual characters later on.
Example Applications:
Classic Undertale AUs (100-Series): A well-known AU like Undertale itself, or a slight variant like Underfell, would have its code defined by one of the 100-series numbers (e.g., 101 for Classic AUs).
A specific AU might be labeled as 101, and any characters from that AU would have numbers such as 101-XXXXXX (with XXXXXX being their unique Personal Channel Code).
Dark Variations (200-Series): An AU that dramatically shifts the tone into darkness, like Underfell, would fall under the 200-series.
For instance, if we decide that aggressive, warped versions are marked as "201", then an AU could be labeled as 201. Characters in this AU would be assigned numbers starting with 201-XXXXXX.
Role-Swap and Playful Variants (300-Series): If an AU like Underswap is chosen for its playful reassignments, it would be assigned a number in the 300-series (e.g., 301).
Then, characters within Underswap would get numbers like 301-XXXXXX.
Experimental Creations (600-Series): Universes that experiment with narrative, mechanics, or physics are allocated the 600-series.
For example, an AU focusing on scientific experimentation such as Handplates would be classified under 603; its characters receive numbers beginning with 603-XXXXXX.
Multiversal & Cosmic AUs (700-Series) and Special Legacy AUs (800-Series): These higher-tier categories are reserved for AUs that transcend the standard narrative or hold mythic status.
A multiversal entity like Ink!Sans might be classified in the 701 subcategory, meaning his number would start with 701-XXXXXX.
Similarly, a godlike character such as GodVerse Sans would belong in the 801 subcategory, with a number beginning with 801-XXXXXX.
Aesthetic-Based AUs (900-Series): For those universes that focus purely on visual or tonal reinterpretations without altering the core narrative, the 900-series is used.
A cinematic or minimalist AU might be classified as 901 or 902, depending on its specific focus.
Historical and Narrative Context
This classification system was designed not only to organize thousands of AUs but also to reflect the evolving nature of the Undertale fandom. As fans continue to explore the possibilities of the narrative, these categories serve as a record of creativity and reinterpretation. Each category tells a story:
The 100-Series captures the essence of the original game, preserving its core while allowing slight deviations that still honor Undertale's original magic.
The 200-Series represents the emotional and thematic extremes—where the bright hope of the original is replaced by darkness, anger, and corruption.
The 300-Series shows how characters and storylines can be playfully inverted, challenging our expectations by swapping roles and reassigning traits.
The 400-Series is a somber reminder that time erodes all things; here, the decay and fading of history are laid bare, inviting reflections on loss and inevitability.
The 500-Series delves into horror—a realm where every comforting aspect of Undertale is turned into a source of terror, and where survival becomes a battle against unspeakable nightmares.
The 600-Series pushes boundaries. These AUs break free from conventional storytelling, mixing genres and playing with reality itself.
The 700-Series steps outside of normal timelines, representing a multiversal synthesis where entities exist beyond the limits of time and space.
The 800-Series honors the mythic, the legendary, and the godlike—AUs and characters whose influence has defined the very fabric of the fandom.
The 900-Series is where artistic expression takes center stage, celebrating pure aesthetics and cultural reinterpretations that may not impact gameplay but resonate on an emotional or visual level.
Each subcategory within these series allows for fine-tuned classification. For instance, in the 100-Series, a "Classic AU Expansion" may further subdivide into variations that are purely narrative expansions versus those that add new gameplay dimensions. This level of detail ensures that every AU is uniquely identified, and that as new AUs are created, they fit seamlessly into the overarching system.
How to Expand and Adapt the System
The beauty of this classification system lies in its scalability. The hundreds and subcategory numbers serve as a framework that can be easily adapted as new AUs are conceived. For example, if a new AU emerges that combines the horror elements of the 500-Series with experimental mechanics from the 600-Series, you can assign it a hybrid classification or choose the one that best represents its dominant themes.
The system is designed to grow organically:
Primary Categories: Each series (100, 200, etc.) represents a core emotional or thematic aspect of the Undertale experience.
Subcategories: Within each series, the last two digits (e.g., 101, 102, etc.) differentiate between various interpretations and nuances.
Personal Channel Codes: Once an AU is assigned a classification, individual characters can then be given a unique six-digit code that extends this identifier. This ensures that every character's Voidsphere Phone Number is unique and traceable back to its AU of origin.
By following this method, you maintain consistency and avoid the overlapping of numbers between different souls. For example, the Patience soul is exclusively within the 10000–19999 range. Similarly, if you assign Justice to the 60000–69999 range, its numbering will not conflict with any AUs in the 100-Series.
Practical Example: Creating a Voidsphere Phone Number for a New AU
Imagine a fan creates an AU called "Underfell Yellow", a darker reinterpretation where Justice is the dominant trait. Given that Justice is in the 600-Series (which we now assign as 60000–69999), and the classic "Undertale Yellow" is reserved for Justice, you might classify it as follows:
Primary Category: Justice (600-Series)
Subcategory: You might decide that "Classic Justice" falls under 60100 (for example) if you designate 60100–60199 for canonical Justice AUs.
Specific AU: "Underfell Yellow" might be assigned the number 60101.
Full Voidsphere Phone Number for a Character: Once you have a Personal Channel Code (say, 000001), the full number becomes 60101-000001.
This process remains consistent regardless of the AU's complexity. The system allows you to maintain a clear record, ensuring that each AU and its associated characters have unique, non-overlapping identifiers.
Final Thoughts on the Classification System
This extended guide not only outlines the core categories and subcategories from 100 to 900 but also provides narrative and practical context for each group. It reflects decades of fan creativity and serves as a living document that can adapt to new ideas as they emerge. The structure is designed to ensure that every AU is categorized in a way that preserves the unique flavor of the Undertale multiverse while providing a robust framework for future expansion.
The system's elegance lies in its simplicity: by allocating distinct numerical ranges for each thematic group, it prevents overlap and confusion. Whether you're cataloging a simple retelling of the original story or a radical, genre-bending reinterpretation, this guide serves as your definitive resource.
As the Undertale fandom continues to evolve, this classification system will remain a testament to the boundless creativity of its community—a meticulously organized roadmap that connects every variation, every twist, and every narrative reimagining in one vast, interconnected multiverse.
May this guide serve you well as you dive deep into the world of AUs, ensuring that every unique interpretation finds its proper place in the grand tapestry of Undertale's infinite possibilities.