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Boatload of Sans by Pudp0n Boatload of Sans :iconpudp0n:Pudp0n 2,807 1,598
A Guide to Undertale AUs
Submissions are temporarily closed. You can still submit, but I won't be adding them in for a while. I just need a little break from everything.
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Click the titles of categories to see more on the AUs listed below them.

Every single character in Undertale is changed. AUs that only affect some of the characters are not found here, nor are AUs that change only during the time Frisk is within the underground.
Basic Change (<-THIS IS A LINK)
The basic theme of Undertale is changed, flipped, or modified while still remaining in the same basic sto
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Undertale Sketchdump 2 AU's by inupuppy1412 Undertale Sketchdump 2 AU's :iconinupuppy1412:inupuppy1412 2,257 184 Choose your Undyne (Undertale AUs) by Toreodere Choose your Undyne (Undertale AUs) :icontoreodere:Toreodere 622 157 Underfell comic by KetrinPetterson94 Underfell comic :iconketrinpetterson94:KetrinPetterson94 1,762 139 I Miss... by Bunnymuse I Miss... :iconbunnymuse:Bunnymuse 1,629 202 Undertale - so many Sanses by TC-96 Undertale - so many Sanses :icontc-96:TC-96 2,127 479 Undertale AU List (Suggestion competition) CLOSED by Toreodere Undertale AU List (Suggestion competition) CLOSED :icontoreodere:Toreodere 1,281 229 Underfell Sans - *Still Determined Kid? by WalkingMelonsAAA Underfell Sans - *Still Determined Kid? :iconwalkingmelonsaaa:WalkingMelonsAAA 4,408 265 A Bunch of Sanses by Dizplicity A Bunch of Sanses :icondizplicity:Dizplicity 1,860 254 La Floof Army by GZ-studio La Floof Army :icongz-studio:GZ-studio 1,810 158 Underfell - Snowdin - 197 by Kaitogirl Underfell - Snowdin - 197 :iconkaitogirl:Kaitogirl 332 357 Choose your sans (Undertale AUs) by Toreodere Choose your sans (Undertale AUs) :icontoreodere:Toreodere 862 497 Gang Is All Here by Bunnymuse Gang Is All Here :iconbunnymuse:Bunnymuse 1,607 169 [Boss] by wolfifi [Boss] :iconwolfifi:wolfifi 2,806 233 Papyrus AU Party by silvergeki Papyrus AU Party :iconsilvergeki:silvergeki 944 108 Get your hands off!!! by tabe103 Get your hands off!!! :icontabe103:tabe103 4,073 454 Is there room for two..(underfell) by Bunnymuse Is there room for two..(underfell) :iconbunnymuse:Bunnymuse 1,306 111 Gaster Gang by Bunnymuse Gaster Gang :iconbunnymuse:Bunnymuse 1,394 157 Sans' Creepy Advice by Sour-Apple-Studios Sans' Creepy Advice :iconsour-apple-studios:Sour-Apple-Studios 1,067 461 Undertale :: Underswap :: Underfell :: PARTY!!! by SpaceJacket Undertale :: Underswap :: Underfell :: PARTY!!! :iconspacejacket:SpaceJacket 2,665 294 Different Timelines, Different Possibilities.. by Kana-The-Drifter Different Timelines, Different Possibilities.. :iconkana-the-drifter:Kana-The-Drifter 2,623 243 Underfell Sans and Papyrus 2 by batata-doce Underfell Sans and Papyrus 2 :iconbatata-doce:batata-doce 1,724 144 their lullaby (underfell) by Bunnymuse their lullaby (underfell) :iconbunnymuse:Bunnymuse 1,632 214 honeymustard gif by tabe103 honeymustard gif :icontabe103:tabe103 1,327 67 Smol Gaster's by Bunnymuse Smol Gaster's :iconbunnymuse:Bunnymuse 1,454 660 Sans' AU Party by silvergeki Sans' AU Party :iconsilvergeki:silvergeki 2,702 532 Undertale :: Underswap :: Underfell:: BRO HUG by SpaceJacket Undertale :: Underswap :: Underfell:: BRO HUG :iconspacejacket:SpaceJacket 1,807 58 Flowerfell 1 by Qin-Ying Flowerfell 1 :iconqin-ying:Qin-Ying 949 141 Undertale :: Underswap :: Underfell:: Lazy Bones by SpaceJacket Undertale :: Underswap :: Underfell:: Lazy Bones :iconspacejacket:SpaceJacket 1,979 162 Gaster's by Bunnymuse Gaster's :iconbunnymuse:Bunnymuse 2,043 217 Underfell - Bloody Monday by lyoth737 Underfell - Bloody Monday :iconlyoth737:lyoth737 1,820 268 Happy Holidays! by ttoba Happy Holidays! :iconttoba:ttoba 4,257 583 Angry UF! Sans by tabe103 Angry UF! Sans :icontabe103:tabe103 3,757 788 Underfell by adricarra Underfell :iconadricarra:adricarra 1,947 160 Sans AU Dump by sheebal Sans AU Dump :iconsheebal:sheebal 2,272 91 I'm sure it wasn't important by Bunnymuse I'm sure it wasn't important :iconbunnymuse:Bunnymuse 872 694 short Underfell comic thing by Wander-Archer short Underfell comic thing :iconwander-archer:Wander-Archer 1,369 87 Choose your Toriel (Undertale AUs) by Toreodere Choose your Toriel (Undertale AUs) :icontoreodere:Toreodere 361 63 Whoa! A horde of Sanses appeared! by The-NoiseMaker Whoa! A horde of Sanses appeared! :iconthe-noisemaker:The-NoiseMaker 2,855 543 Mistakes Were Made by Bunnymuse Mistakes Were Made :iconbunnymuse:Bunnymuse 865 383 Underfell - The Good Inside - pg 8 END by THEpinknekos Underfell - The Good Inside - pg 8 END :iconthepinknekos:THEpinknekos 1,394 249 Altogether Now by Bunnymuse Altogether Now :iconbunnymuse:Bunnymuse 875 67 UNDERFELL sans by tabe103 UNDERFELL sans :icontabe103:tabe103 1,643 429 Underfell Papyton 2 by YAMsgarden Underfell Papyton 2 :iconyamsgarden:YAMsgarden 4,225 225
 If you haven't heard of Underfell, please check it out. I find it interesting! It's an AU where everything is in reverse.
    "You're really determined, aren't you?" Sans hissed mockingly, his shoulders bouncing with a low chuckle as he loomed above Frisk, his crimson eye glowing maliciously. A smug grin was spread across his features, and he let out a snort as Frisk heaved themselves to their feet, biting down on their lip to swallow a whimper.
    Their face was damp with tears, bruises littering their skin- but the fierce persistence in their dark eyes never faded. Clenching their jaw against the tightness in their chest, they shuddered against the cold and curled their fingers into fists. The frigid wind blew on, and the seemingly never ending expanse of gelid white was only broken by Sans' stark, blood red aura and the jagged shadows of the skeletal trees behind them.
    The silence was only broken by Frisk's s
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Kill or Be Killed by Seadraz Kill or Be Killed :iconseadraz:Seadraz 187 30 Undertale :: Underfell:: SHOCKING by SpaceJacket Undertale :: Underfell:: SHOCKING :iconspacejacket:SpaceJacket 1,540 208 [Ask Out] by wolfifi [Ask Out] :iconwolfifi:wolfifi 1,472 106