Undertale, but all the AU's are actually different games made off like Undertale, like uh... Sonic games!

Games in chronological order (what came first)

𝗨𝗻𝗱𝗲𝗿𝘁𝗮𝗹𝗲 is the Classic.

𝗨𝗻𝗱𝗲𝗿𝘀𝘄𝗮𝗽 was released on opposite day.

𝗨𝗻𝗱𝗲𝗿𝗳𝗲𝗹𝗹 was made with edge in mind. (like shadow games, the dark horse)

Haventale (multiplayer where no human souls are taken, but you cant ever leave the underground. Hide and seek with NPCs and other players are available.)

𝗖𝗮𝘁𝘁𝗮𝗹𝗲 (for the cat lovers of course! They were planning a dog game but decided against it...)

𝗗𝘂𝘀𝘁𝘁𝗮𝗹𝗲 (were SOMEONE goes crazy from all the genocide resets and thinks they can only win one way)

𝗗𝗮𝗻𝗰𝗲𝘁𝗮𝗹𝗲 (for all those dance dance revolution fans! You have to have the full body thing for VR though... This game can teach you to dance whatever style you want as long as you try hard enough!)

𝗛𝗼𝗿𝗿𝗼𝗿𝘁𝗮𝗹𝗲 (was made to be a literal horror game for... Yeah, I see you. Freaks.)

𝗕𝗶𝘁𝘁𝘆𝘁𝗮𝗹𝗲 𝗕𝗶𝘁𝘁𝘆𝗯𝗼𝗻𝗲𝘀 (a multiplayer platform where you can live a day to day life with a bitty of your own! A person can only have up to 4 bitties so choose wisely! Originally named bittytale but the players demanded it to be changed to bittybones.)

𝗞𝗶𝗹𝗹𝗲𝗿𝘁𝗮𝗹𝗲 (were our ghost companion is actually a demon, gets bored, and convinced someone to kill everyone, it's like a murder mystery. Also, released on Easter)

𝗠𝗮𝗳𝗶𝗮𝘁𝗮𝗹𝗲 (for the ones who want angst and family as they got mommy or daddy issues, with a side of murder mystery)

𝗙𝗹𝗼𝘄𝗲𝗿𝗳𝗲𝗹𝗹 (unlike most of the games, this one you get a limit of tries you can take! Oh, and you get a romance with the sans of this one if you try hard enough to interact with him! The franchise hated this one and wanted to delete it though...)

𝗘𝗰𝗵𝗼𝘁𝗮𝗹𝗲 (a thirst trap with lore hidden all around, explaining the Multiverse theory and having a bunch of Easter eggs, and released on Easter just to tease people even more.)

𝗔𝘀𝘆𝗹𝘂𝗺𝘁𝗮𝗹𝗲 (You can choose to be a nurse or a patient! Slightly horror themes though...)

𝗠𝗮𝗳𝗶𝗮𝗳𝗲𝗹𝗹 (basically a shooting game with how much those fighting cutscenes happen)

𝗦𝘄𝗮𝗽𝗳𝗲𝗹𝗹 (purple version, like pokemon)

𝗙𝗲𝗹𝗹𝘀𝘄𝗮𝗽 (red version, like pokemon)

𝗗𝗿𝗲𝗮𝗺𝘁𝗮𝗹𝗲 was slightly strange game (it was made for self awareness and to show people shouldn't bully others because they are different.)

𝗣𝗼𝗸𝗲𝘁𝗮𝗹𝗲 (with the permission of the creators of Pokemon, the Undertale franchise made a game for the pokemon lovers in the franchise, where monsters and humans are in peace and catching pokemon together!)

𝗨𝗻𝗱𝗲𝗿𝗹𝘂𝘀𝘁 (not for those under the age of 18, MDNI. Released on the day before Valentine's, so some people wouldn't be lonely)

𝗨𝗻𝗱𝗲𝗿𝗳𝗿𝗲𝘀𝗵 (this game is unstable, and may seem happy but be warned, you shouldn't be near the sans for too long... Actually, try to avoid all the residents infected with neon colors.)

𝗔𝗳𝘁𝗲𝗿𝘁𝗮𝗹𝗲 (just a chat game where you talk to an AI named Geno, that, when used to you, slowly gives out hints of lore about why they are in this void, where their game used to be)

𝗨𝗻𝗱𝗲𝗿𝗺𝗼𝗻 (monsters are pokemon!)

𝗘𝗽𝗶𝗰𝘁𝗮𝗹𝗲 (with EPIC fighting scenes for the anime lovers)

𝗗𝗲𝗺𝗼𝗻𝘁𝗮𝗹𝗲 (the underground is actually hell, and monsters are demons)

𝗹𝗶𝘁𝘁𝗹𝗲𝘁𝗮𝗹𝗲 (more of an kids educational game, and you can choose your grade level before hand and you learn with the monsters of the underground! 1st grade to 4th grade only tho [education mode optional])

𝗢𝘂𝘁𝗲𝗿𝘁𝗮𝗹𝗲 (mostly known for it's wonderful artwork, but is an educational game as well! 5th to 8th grade! [education mode optional])

𝗫-𝗘𝘃𝗲𝗻𝘁 (it's like a CROSSover of some of the popular games in the franchise)

𝗦𝗰𝗶𝗲𝗻𝗰𝗲𝘁𝗮𝗹𝗲 (another educational game, but for 9th grade to college [education mode optional])

𝗡𝗮𝗴𝗮𝘁𝗮𝗹𝗲 (Snake Bois 🐍)

𝗦𝗶𝘅𝗯𝗼𝗻𝗲𝘀 (a sade tale and an angsty game, like horrortale! Perfect for the freaks of the franchise-)

𝗙𝗲𝗹𝗹𝗳𝗿𝗲𝘀𝗵 (where the UNFRESH people resides! PUNKS!!)

𝗥𝗲𝗮𝗽𝗲𝗿𝘁𝗮𝗹𝗲 (kinda like God of War games?)

𝗖𝗿𝗼𝘀𝘀𝘁𝗮𝗹𝗲 (a prequel to X-Event, released after X-Event to tease the People who wanted to see more lore)

𝗗𝗿𝗲𝗮𝗺𝘀𝘄𝗮𝗽 (was released a year after Underswap, on opposite day to celebrate the franchise's success)

𝗡𝗶𝗴𝗵𝘁𝗺𝗮𝗿𝗲'𝘀 𝗥𝗲𝗮𝗹𝗺 (another Rare replay inspired one, and only hold the "violent games" that the gang are from. Has some cutscenes of the Nightmare gang just vibing, being friends, and hanging out if you wait long enough, like their waiting for you to start up their game so they decided to do something more fun for a moment)

𝗢𝗺𝗲𝗴𝗮 𝗧𝗶𝗺𝗲𝗹𝗶𝗻𝗲 (a game that actually have most of the timeline games available on it, like Rare Replay, with Core Frisk as a guide!)

𝗗𝗼𝗼𝗱𝗹𝗲𝘀𝗽𝗵𝗲𝗿𝗲 (a game that actually has most of the AU games available on it, kinda like the Omega Timeline but with -꒐ꋊꀘ- as the guide!)

𝗔𝗻𝘁𝗶-𝗩𝗼𝗶𝗱 (the last game of the franchise. A void with an AI that is kinda like Geno, but not as much lore and is more focused on explaining the AU's, the AI is called Ɛ尺尺Ø尺 and they could show you 𝞔𝔯𝔯օ𝔯 from all of the games in the franchise... But if you want the cutscenes you got to pay for the cutscenes... Or sell your soul to the franchise)

𝗙𝗮𝘁𝗮𝗹_𝗘𝗿𝗿𝗼𝗿 (were the AI in Aftertale gets corrupted after having a run in with Error, A timeline game)

Now after this it gets a bit weird, as some AU's are if the NPC acts different, showing different routes, like how Dusttale was an alternate timeline of Undertale.

Timeline games are made with the AU game it's based off in mind, and it has some of the same lore as the AU game it's based off. And Mixed AU's like Swapfell would be... An AU game that takes traits from both AU's. (like the AU's would be parent AU games to that game.) Also, timeline games are side games that are just for fun.

Killertale and Dusttale are like cousins, with the same uncle.

I think in this idea the Franchise would have a saying like,

" We aim to please all of our audience! So do enjoy the games!"

And the franchise would hide something like the FNAF franchise did in game, like how they needed 7 human souls to make the original game. They need 7 for each game...

Yeah the franchise is slightly evil...

I just finished playing Bonely Hearts and Just An Experiment and they both just killed me! Like, my heart is in disarray rn lmfao

Especially "Just An Experiment", Dr. Baggs has completely taken over my heart, holy moly-

I freaking loved it!!!! Like wtffff

Whoever recommended that to me (you know who you are) I hope you know that you just made my sans simping heart delusions worse 😂

No but fr, thank you for recommending that to me, I freaking adored it, I spent like 4 hours non-stop to get all the endings lmfao

💙💙💙

There's a spoiler for one of the endings under the cut!!!

You've been warned!