Basically Belowexchange's soundtrack & "Moonstriker the Musical: underswap"'s soundtrack combined, with MtM first (because it released first). Includes older versions & covers because that's how I roll.

MtM: U logo & soundtrack made by Moonster
BE logo made by SylviaTheGhost (https://soundcloud.com/spiritualworks)
BE made by Quicksilver (Slick Silver x Dashingtoadie)
Beautiful logo combination by me

bowser man challenge: make playlist without using moonster tracks (impossible)

Quickstriker the Musical: Belowexchange + underswap

Slick's Contests: The Complete Collection

If you press "U", this leitmotif will play.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Undertale was created by Toby Fox
In an alternate universe, 'Underswap' was created by Temmie Chang
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Leitmotif:
- Uwa!

☂ Ting-a-ling ☂

Name the fallen human
"FRISK".
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Undertale was created by Toby Fox
In an alternate universe, 'Underswap' was created by Temmie Chang
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Leitmotif:
- Ruins
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Yep, Frisk is still the first fallen human here! You play as Chara. On the other hand, "Determination" swaps with "Hope". Which means, "Hope" is the core trait of every human being. Chara benefits a lot of hope and possesses the soul of "Courage".

☂ An Empty Stream of Progress ☂

*It's a pile of blue glowing mushrooms.
*They must've softened your swift impact.
*Nowhere to go but forward.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Undertale was created by Toby Fox
In an alternate universe, 'Underswap' was created by Temmie Chang
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Leitmotif:
- None
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Yep, this is the "wind" replacement. Additionally, Waterfall swaps with the Ruins, more specifically, the Garbage Dump swaps with the Starting Point and the mushrooms swap with the golden flowers. If you fall onto them, you'll find yourself in a beautiful and serene atmosphere of the sanctuary... well not when you're in the start of it since there'd be garbage all over the place. And just as importantly, have "faith" in yourself to the end!

☂ Waking up in the Garbage Dump ☂

*Long since, two races reigned over the EARTH: HUMANS and MONSTERS.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Undertale was created by Toby Fox
In an alternate universe, 'Underswap' was created by Temmie Chang
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Leitmotif:
- Ruins(/Battle Against a True Hero)
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Since it's related to the intro, the barrier swaps with the gate entrance from the Ruins, and Mt. Ebott swaps with Mt. Emmett (which is actually real mountain if you search it up =P)Like Toby's old plan, Chara's going to seek for a refugee from a heavy rain outside, which explains why it'll be raining in the sanctuary. Chara will be donning a cute green raincoat and bring an umbrella as a... weapon.
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Third update! Remember the very first version of "Left in Ruins"? Yeah, this is a combination of the two which additionally uses genesis soundfont to stay consistent with the technical SEGA and Nintendo swap.

☂ Left in Ruins ☂

underswap, a game where a truly happy ending is possible! Only if you choose so.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Undertale was created by Toby Fox
In an alternate universe, 'Underswap' was created by Temmie Chang
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Leitmotif:
- Ruins
- Song That Might Play When You Fight Sans
- It's Raining Somewhere Else

underswap - Putting a Little More 'Backbone' into It (Trailer)

Edit: Welp, I fucking lost, but atleast I got an honorable mention, so yay?

An entry for Slick Silver's Birthday Contest (@slick_silver)

The Joy of Reversion is a revertswap take made by @slick_silver now owned by me and @ericmakesweirdmusic

Motifs:
Hopes and Dreams - Undertale
His Theme - Undertale

Credits:
Undertale by Toby Fox.
Revertswap by ???
The Joy of Reversion by @slick_silver owned by me and @ericmakesweirdmusic

Advertisements:
A Tale of Danmaku Discord: https://discord.gg/bN3yg4P
Gateway to Gensokyo Discord: https://discord.gg/9z2GYsr
Silvulus Studios Hub Discord: https://discord.gg/CNEscvd

[The Joy of Reversion] - A Tale Long Ago, Now Reverted [Slick's Birthday Contest]

*...
*Oh.
*Another one of you.
*I wasn't expecting that.
*...well howdy.
*I'm FLOWEY.
*FLOWEY the FLOWER.

Aftergore is a series of AUs taking place after Undertale's neutral endings, in which a new human enters in Frisk's wake.
Aftergore I, the Incomplete/Flawed Pacifist ending, details an ending in which everyone (except for Asgore) was spared and befriended. Toriel has taken her ex-husband's place, ruling the Underground with both strictness and kindness. Humans are to be treated not as enemies, but as friends.

Flowey takes the role of Toriel. After being spared by Frisk, he's been doing a lot of soul searching (no pun intended). He's hidden away in the Ruins, which is now overgrown with vegetation and fear. He might be turning over a new leaf (again, no pun intended), but it's hard to let go of the fearsome persona he has worked so hard to build. Could he ever truly qualify as a "caretaker?"

Learn more about Aftergore and other projects here! discord.gg/qmtQxwYKfD

Aftergore logo by @repeatsc and Toadie
Flowey sprite by Toadie

[Aftergore I] Afraid and Confused

New version: https://soundcloud.com/toadiedoesalltheworktbh/schreibertale-the-way-things-were-2

(Outdated) [Schreibertale] The Way Things Were

Another @slick_silver contest entry! I originally wanted to complete the Talebreak trio, but I resorted to this instead.
Enjoy!

[BelowExchange] Empty Hopes, Empty Dreams (Children's Day Contest)

*Hey there, paisano.
*You're one of those Miis, ain'tcha?
*Don't worry, I get it. I'm kind of new here myself.
*You can call me the Piranha Plant.

Gorgeous thumbnail by @austhetic.

Yes. I, Slick Silver, have a Smashtale take. I have never had one of these before, nosiree.
I didn't actually expect anyone to make anything for this. Dunno if it'll go anywhere, or even if I want it to. But I have it. This is another contest entry from Toadie, posted here to save minutes. Enjoy.

[Smashtale: Lights Out] Pesky Pipe Plant

Thank you to @supersilvulusparttwo for letting me reupload this!

This AU, owned by @supersilvulusparttwo, @ericmakesweirdmusic, and @slick_silver, is a "take" on Revertswap/Swapswap, in which characters were put through a "swap timeline" and then brought back to their original personalities and positions with faint memories of the experiences they went through. Flowey's done a lot of thinking and now lives a more peaceful life maintaining the Ruins, now that his parents are back together in the Capital.

Don't expect too much from this AU, to be frank we don't have time to give it much attention right now. Maybe someday though.

(Guest Track - SpiritualWillow) [The Joy of Reversion] Blooming Friendship

!!! I AM INACTIVE HERE, YOU CAN FIND MY SOCIALS AND NEWER MUSIC IN MY LINKTREE BELOW !!!

I'm Jae/Ayz, but calling me Soul or Kae is fine too. 
My pronouns are She/They/It/Any Neos but you probably already read that
My gender is female/shadowgender (or just “shadowgirl”)
I use LMMS to make music.

I should actually describe myself this time lmoa
I’m obsessed with Undertale/Deltarune, Vocaloid stuff, and Friday Night Funkin
And probably more but I can’t be bothered to remember 

My music is half original, half fan-content. The fan-content is usually gonna be Undertale/Deltarune 
My Youtube (linked below) has some archived songs among other random things.

Uhhhh I’ll add more if I can think of anything bye lol

[BelowExchange] Empty Hopes, Empty Dreams (Children's Day Contest)

[INACTIVE] SimplySoulbound | Jae/Ayz