Below is the comprehensive Voidsphere AU Classification Guide—a living document that assigns a unique phone classification code to every known Undertale Alternate Universe (AU) as envisioned for the Voidsphere Phone. This guide is designed to serve as the foundational framework for generating full Voidsphere Phone Numbers (VSPNs) later. Each AU is given a code made up of a Dimensional Prefix and a Universal Identifier (U-ID), which together capture the thematic essence and narrative flavor of that AU. Note that individual Personal Channel Codes (six-digit numbers unique to each character) will be appended later during specific interactions. For now, we focus solely on the AU-level classifications.
──────────────────────────── The Voidsphere Classification System
Each Voidsphere Phone Number (VSPN) is structured as follows:
[Dimensional Prefix] – [Universal Identifier] – [Personal Channel Code]
• The Dimensional Prefix designates the broad category or thematic family to which the AU belongs.
• The Universal Identifier (U-ID) is a unique four-digit code assigned to that specific AU.
• The Personal Channel Code will later be a unique six-digit identifier for each individual.
For our purposes here, we assign the following Dimensional Prefixes to the AU groups:
• "100" – Classic/Original Undertale AUs
• "200" – Dark or Angrier reinterpretations
• "300" – Playful role-swap variations
• "400" – AUs defined by decay, erosion, or fading existence
• "500" – Horror, gloom, and unsettling reimaginings
• "600" – Experimental, radical, and unorthodox creations
• "700" – Underverse – for those entities that exist outside conventional AU boundaries (multiversal originals)
• "800" – Special, Omega Tier, and Legacy AUs (god-tier, mythic, narrative-defining)
• (Additional prefixes, if needed, such as "900" for certain aesthetic or visual reinterpretations.)
──────────────────────────── Classification System for Human Souls
• "10000" Series: Patience (Light Blue)
• "20000" Series: Bravery (Orange)
• "30000" Series: Integrity (Blue)
• "40000" Series: Perseverance (Purple)
• "50000" Series: Kindness (Green)
• "60000" Series: Justice (Yellow)
Below is an extensive listing of every known AU, organized into thematic sections. Each entry includes the assigned classification code (Dimensional Prefix – U-ID) along with a brief description.
──────────────────────────── I. Role-Swap and Personality Shift AUs
These AUs primarily alter character roles, personalities, or narrative functions, often by swapping them with one another in creative and unexpected ways.
Underswap
Classification Code: 300-0001
Underswap reimagines the original characters by exchanging roles and temperaments. Familiar faces take on new occupations and attitudes, resulting in a universe that is playful, ironic, and rich with subtext.
Storyshift
Classification Code: 300-0002
Storyshift deepens the role-swap concept by overhauling the narrative itself. Characters adopt radically different roles, and the story's structure is transformed into an intricate tapestry of altered destinies.
Swapfell
Classification Code: 200-0001
Swapfell merges role-swap ideas with the dark, brooding atmosphere typical of more corrupted worlds. Here, characters not only swap roles but are imbued with a bitter, tragic intensity.
Fellswap
Classification Code: 200-0002
Fellswap offers a variant on Swapfell, with a different blend of inversions and darker themes. It creates a universe where irony and despair interlace, turning familiar personalities into symbols of lost hope.
Swaptale
Classification Code: 300-0003
In Swaptale, the emphasis is on gentle subversion of roles without the overt darkness of Underfell. The AU presents a playful reinterpretation that remains endearing and light-hearted.
Shiftfell
Classification Code: 200-0003
Shiftfell combines the role reversal of Swaptale with the harsher narrative tones of Underfell. Characters here are caught between mirth and misery, resulting in a constantly shifting emotional landscape.
──────────────────────────── II. Theme-Based AUs
These universes take the core setting of Undertale and transplant it into entirely new thematic environments.
Outertale
Classification Code: 800-0001
Outertale places the Underground within the vast expanse of space. Here, cosmic phenomena and interstellar mysteries shape the narrative, blending magic with astronomical wonder.
Undersea
Classification Code: 800-0002
Undersea reimagines the Underground as an immense aquatic realm. Characters are reinterpreted as denizens of a mysterious deep, where water, coral, and marine life dominate the landscape.
Underkeep
Classification Code: 800-0003
Underkeep transforms the setting into a medieval fortress, where castles, knights, and ancient lore redefine every interaction. The architecture is grand and imposing, a testament to chivalry and legacy.
Underlust
Classification Code: 800-0004
Underlust delves into mature themes of desire and passion. This AU explores the complexities of relationships and emotions in a realm where every connection is charged with a heightened sensuality and intrigue.
Underforest
Classification Code: 800-0005
Underforest envisions the Underground as a sprawling, enchanted woodland. Nature and magic intertwine, and characters are reinterpreted as part of a living, breathing ecosystem where growth and decay coexist.
Understeam
Classification Code: 800-0006
Understeam infuses the setting with steampunk aesthetics. Victorian-era technology, gears, and steam merge with arcane elements, creating a universe of innovation, rebellion, and mechanical wonder.
Underpunk
Classification Code: 800-0007
Underpunk injects a raw, anarchistic energy into the Underground. With a focus on punk culture and countercultural attitudes, this AU is gritty, rebellious, and vibrantly defiant.
Undergrave
Classification Code: 800-0008
Undergrave casts the Underground in gothic tones, emphasizing decay, mourning, and eerie beauty. The atmosphere is one of perpetual twilight, with every corner steeped in sorrow and mystery.
Underfrost
Classification Code: 800-0009
Underfrost reimagines the world as an arctic wasteland, where ice and snow dominate. Here, the cold is both a physical and emotional force, challenging characters to endure against nature's relentless chill.
Underhot
Classification Code: 800-0010
Underhot provides a stark contrast to Underfrost by portraying the Underground as a blazing desert or volcanic realm. Heat, shifting sands, and molten rock define this universe, where survival depends on harnessing fiery energy.
──────────────────────────── III. Character-Centric and Narrative-Altered AUs
These AUs focus on transformative narratives and reinterpretations of character destinies, often emphasizing dramatic shifts in tone and purpose.
Horrortale
Classification Code: 500-0001
Horrortale is a universe drenched in terror and despair. The familiar characters are reimagined as figures of horror, where every interaction is infused with dread and a haunting inevitability.
Dusttale
Classification Code: 400-0001
Dusttale presents a realm where decay and the slow erosion of hope are central themes. Characters here are depicted as fading echoes of their former selves, their determination worn thin by time and entropy.
Aftertale
Classification Code: 400-0002
Aftertale explores the aftermath of a Genocide run. This AU is marked by reflection, remorse, and the difficult task of rebuilding from the ruins of past decisions.
Errortale
Classification Code: 600-0001
Errortale introduces a chaotic, corrupted timeline where glitches and digital decay twist the fabric of reality. Error!Sans serves as its emblem, and the AU is characterized by a constant state of flux and instability.
Inktale
Classification Code: 700-0001
Inktale reimagines the Underground as a living canvas, where art and creativity are central. Ink!Sans is the patron of this realm, and every element of the AU reflects the transformative power of artistic expression.
Underfresh
Classification Code: 700-0002
Underfresh showcases a rejuvenated, vibrant reinterpretation of the classic characters. This AU infuses its contacts with youthful energy and optimism, revitalizing familiar faces with a modern twist.
Dreamtale
Classification Code: 700-0003
Dreamtale centers on the interplay between dreams and reality. Characters are imbued with ethereal qualities, and the narrative explores the boundaries between aspiration and the subconscious.
Nightmaretale
Classification Code: 700-0004
Nightmaretale is the darker mirror of Dreamtale, where fears and nightmares manifest in tangible forms. This AU is a study in the balance between hope and terror, with each call evoking both allure and dread.
Underpatch
Classification Code: 700-0005
Underpatch gives the Underground a patchwork, fragmented aesthetic. Characters appear stitched together from remnants of their past, their very existence a collage of memories and lost identities.
Underfallen
Classification Code: 700-0006
Underfallen focuses on the theme of decline and the struggle for redemption. Here, heroes are tarnished by suffering, and every connection is imbued with the bittersweet yearning to reclaim lost glory.
Underbright
Classification Code: 700-0007
Underbright is a universe that shines with inner light even in the midst of darkness. Characters radiate hope and resilience, and the classification code symbolizes a beacon of unwavering determination.
──────────────────────────── IV. Crossover and Aesthetic-Based AUs
These AUs arise from crossovers with other fandoms or are defined by distinctive visual and aesthetic reinterpretations.
Underwatch
Classification Code: 800-0001
Underwatch merges the Undertale universe with high-octane, contemporary action. Characters are recast as heroes and antiheroes locked in dynamic battles, with a tone that is both modern and epic.
Pokétale
Classification Code: 800-0002
Pokétale fuses the Underground with elements of the Pokémon universe. Characters take on roles reminiscent of trainers and creatures, creating a vibrant, energetic setting where strategy meets the wild unpredictability of nature.
Underheroes
Classification Code: 800-0003
Underheroes redefines classic figures as champions and defenders with superhuman abilities. The narrative is one of epic conflict, where every contact is a call to battle in defense of a multiversal order.
Underleague
Classification Code: 800-0004
Underleague imagines the Underground as a competitive arena reminiscent of modern eSports or MOBA dynamics. This AU is defined by structured tournaments and high-stakes battles, with a keen focus on strategic prowess.
Undercraft
Classification Code: 800-0005
Undercraft merges the creativity of sandbox worlds with the rich lore of Undertale. Here, building and engineering are woven into the narrative, allowing characters to construct worlds and fortresses out of both digital and arcane materials.
Underwatch (Alternate Crossover)
Classification Code: 800-0006
In some interpretations, Underwatch is reimagined with an emphasis on cybernetic enhancements and tactical warfare. Though sharing a name with its other variant, this code distinguishes a universe where futuristic technology drives the narrative.
──────────────────────────── V. Aesthetic and Visual Reinterpretation AUs
These universes focus primarily on a distinctive visual style that reinterprets the classic characters and settings through a particular color scheme or artistic lens.
Underpurple
Classification Code: 900-0001
Underpurple is defined by its dominant violet and indigo hues. In this AU, every element is tinted with regal, mysterious shades that evoke an air of sophisticated melancholy and otherworldly grace.
Underneon
Classification Code: 900-0002
Underneon infuses the Underground with cyberpunk energy. Neon lights and digital aesthetics collide with dark urban decay, creating a vibrant yet edgy universe pulsing with modern electricity.
Undersepia
Classification Code: 900-0003
Undersepia strips the world of vibrant color, presenting a vintage, nostalgic interpretation. The sepia tones evoke memories of a bygone era, where every contact feels like a whispered recollection of history.
Underpixel
Classification Code: 900-0004
Underpixel reinterprets the universe in retro, pixel-art style. This AU pays homage to the early days of gaming, blending simplicity with a charming, digital aesthetic.
Underchroma
Classification Code: 900-0005
Underchroma emphasizes shifting, vibrant hues that morph continuously. In this ever-changing kaleidoscope, every number is a vibrant splash of color, symbolizing the fluidity of existence.
Underpastel
Classification Code: 900-0006
Underpastel softens the world's palette to gentle, muted colors. This AU offers a calming, dreamlike interpretation where each contact exudes a serene and soothing energy.
Undergrayscale
Classification Code: 900-0007
Undergrayscale removes all color, leaving a stark, monochromatic universe. Here, the absence of hue forces one to focus on form, light, and shadow—a raw portrayal of the underlying truths of existence.
Underglitch
Classification Code: 900-0008
Underglitch celebrates intentional visual distortions. Digital errors and visual glitches are woven into the very fabric of this AU, creating a realm where chaos and beauty intertwine in unexpected ways.
────────────────────────── VI. Story-Altered and Narrative Reinterpretation AUs
These AUs are driven by significant alterations in the storyline and character destinies, often exploring themes of loss, renewal, and cyclical fate.
Reapertale
Classification Code: 600-0002
Reapertale envisions the Underground as a realm ruled by death and the passage of souls. Characters take on roles as reapers and guardians of the afterlife, where endings merge with new beginnings.
Underdecay
Classification Code: 600-0003
Underdecay portrays a universe where time corrodes everything. The characters and structures of the Underground are worn by relentless entropy, making every connection a struggle against inevitable deterioration.
Understuck
Classification Code: 600-0004
Understuck depicts a static reality—one where events are trapped in an endless loop. In this AU, progress is halted and fate seems predetermined, offering a haunting meditation on the nature of change.
Underbroken
Classification Code: 600-0005
Underbroken presents a shattered, fragmented world. The very fabric of reality has splintered, and the characters are forced to piece together their identities from the remnants of a broken past.
──────────────────────────── VII. Experimental and Unorthodox AUs
These AUs arise from radical reinterpretations and avant-garde experimentation in the Void Lab, challenging every convention.
Experimental AU
Classification Code: 600-0010
This category is reserved for AUs born from bold, unorthodox experiments. The rules of the original narrative are upended entirely, yielding creations that are as unpredictable as they are innovative.
Experimental Act
Classification Code: 600-0011
A further refinement of the experimental concept, Experimental Act features deliberate, boundary-pushing reimaginings of characters and settings. It is a realm where "what if" scenarios become the norm, and every outcome defies expectation.
──────────────────────────── VIII. Underverse – The Multiverse's Own Domain
Underverse is a unique classification for entities and universes that exist outside of conventional timelines and AUs. It serves as the umbrella for those beings whose existence transcends standard narrative constraints.
Underverse
Classification Code: 700-0001
Underverse is reserved for contacts who roam the multiverse without being bound to any single AU. This classification encompasses legendary figures, anomaly-keepers, and mythic entities whose origins are as fluid as the cosmos itself.
──────────────────────────── IX. Special, Omega Tier, and Legacy AUs
This final category is dedicated to the most exceptional, god-tier entities and the universes that have reshaped the very fabric of existence. These are the contacts that carry immense narrative weight.
Special Omega Tier
Classification Code: 800-0001
This code is for supreme entities and universes whose influence spans countless realities. It marks contacts of unparalleled power and mythic significance.
King Multiverse
Classification Code: 800-0002
Assigned to AUs or entities that epitomize dominion over the multiverse, this classification is reserved for those whose authority is absolute.
Alpha/Ao (Primordial) AUs
Classification Code: 800-0003
These universes delve into the origins of the Underground. They capture the raw, unrefined energy of creation—a time when every contact was forged in the crucible of pure, elemental determination.
──────────────────────────── X. Additional Fan-Created and Expanded AUs
In response to the ever-growing creativity within the Undertale community, the following AUs have been added to further enrich the Voidsphere directory. These entries embrace diverse themes—from digital distortions to floral beauty—and each is given its own unique classification code according to the Voidsphere system.
Glitchtale
Classification Code: 600-0012
Glitchtale is a universe where the boundaries between code and reality blur. Here, familiar characters are reimagined as digital specters, their forms marred by sporadic glitches and unpredictable data disruptions. Every element of this AU pulses with a raw, erratic energy, as if the very fabric of the Underground is caught in a constant state of reprogramming. Glitchtale stands as a testament to technological decay and renewal, inviting its users to explore the beauty of imperfection in a world where error becomes art.
Dancetale
Classification Code: 600-0013
In Dancetale, the Underground is transformed into a vibrant, rhythm-driven arena. Music and movement reign supreme, and every interaction is a choreographed celebration of determination. Characters here communicate through dance moves and musical cues; battles are fought with synchrony and timing rather than brute force alone. Dancetale's atmosphere is electric, where each step, each beat, becomes a call to unity and creative expression—a realm where strategy and artful movement merge.
Underdoom
Classification Code: 600-0014
Underdoom presents a stark, apocalyptic reinterpretation of the Underground. In this universe, despair is not merely a shadow but the dominant force; hope is scarce and every moment is tinted with impending tragedy. The characters are depicted as harbingers of doom, their determination weighed down by a crushing sense of inevitability. Underdoom's environment is barren, its architecture crumbling under the weight of existential despair, making every call from this realm a somber meditation on the impermanence of existence.
Underheart
Classification Code: 700-0008
Underheart focuses on the profound emotional bonds that define the multiverse. In this AU, the strength of a soul is measured not just in determination but in the capacity to feel deeply. Characters are reimagined as sensitive, empathetic beings whose interactions radiate warmth and compassion. The landscape of Underheart is lush with symbolism—vibrant hearts interlace with tender, pulsating energy—and every connection made is imbued with the potential for healing and profound personal growth.
Underdrift
Classification Code: 900-0009
Underdrift is a universe where the laws of physics are fluid, and reality itself is in constant motion like particles caught in a cosmic current. This AU's environment shifts continuously, with landscapes that seem to drift in and out of focus. Characters appear almost ethereal, their forms blurred by the perpetual motion of the cosmos. Underdrift's classification reflects a state of perpetual flux—a realm where boundaries dissolve and every call feels like a journey through a dreamlike, ever-changing horizon.
Flowerfell
Classification Code: 900-0010
Flowerfell reinterprets the Underground as a realm where flora dominates. Here, every character is adorned with floral motifs, and the environment bursts with organic patterns reminiscent of a garden in perpetual bloom—even as underlying tragedy pervades the narrative. The aesthetic is both beautiful and bittersweet; delicate petals and vibrant blossoms contrast sharply with the harsh realities of determination and loss. Flowerfell's number is a tribute to the fleeting beauty of life, where even decay can give rise to new growth.
Requiemtale
Classification Code: 500-0002
Requiemtale is a mournful AU dedicated to the elegiac remembrance of the Underground's past. In this realm, every character's story is tinged with sorrow and longing, their voices echoing like distant laments. The atmosphere is somber, with a pervasive sense of loss that is both tragic and transcendent. Requiemtale's classification underscores a universe where every call is a requiem—a final, heartfelt tribute to what has been and what can never be reclaimed.
OverTale
Classification Code: 800-0007
OverTale offers a radical inversion of the traditional Underground. In this AU, the familiar setting is elevated to an "overworld" where characters inhabit a realm of grandiosity and high society. The architecture is opulent, the narrative is imbued with a sense of lofty ambition, and every connection seems charged with an air of regal command. OverTale's code reflects a universe where the boundaries between class, power, and destiny are completely redefined, inviting players to explore an alternate vision of what it means to rule.
──────────────────── UltSans' Special Contact (Separate from AU Classifications)
UltSans, the architect of the Void and the creator of this entire multiversal network, is set apart from the standard AU classifications. His contact number is not assigned a conventional AU code, as his presence transcends every single timeline and universe.
• UltSans' Voidsphere Contact is reserved under its own unique designation:
Dimensional Prefix: 888
Reserved Unique Identifier: 0000
This special number "888–0000–000000" stands as the ultimate key to interdimensional wisdom, power, and creation—a beacon for all who traverse the Void. It is not part of the standard directory but is instead recognized as the foundational call to the architect of the multiverse.
──────────────────────── Final Remarks on the Voidsphere AU Classification Guide
This guide represents a chronicle of every known Undertale AU as it currently exists in the collective creative consciousness of the fandom. Each classification code is designed to capture the essence of its AU—whether it be the playful subversion of roles in Underswap, the dark tragedy of Underfell, the decaying melancholy of Dusttale, or the radical innovation of the Experimental AUs. The Underverse category embraces those transcendent entities that defy conventional narratives, while the Special Omega Tier honors the mythic, legacy-defining universes that shape the destiny of the multiverse.
As new AUs emerge and reinterpretations evolve, this guide will continue to expand. It is a living document—a testament to the boundless creativity of the community and the ever-shifting tapestry of existence in UltSans's vision. When you later assign individual Personal Channel Codes, every full Voidsphere Phone Number will serve as a conduit for conversation, collaboration, and the exchange of cosmic wisdom across the infinite expanse of time and space.
May this Voidsphere AU Classification Guide serve as your interdimensional map—a detailed record that opens the door to countless universes, each a vibrant thread in the grand tapestry of the multiverse. And may every call made through the Voidsphere Phone echo as a testament to the timeless magic and boundless creativity that define Void Dominion.