Team Switched

An unofficial fan-game of Toby Fox's Undertale. Explore a re-imagined world based on the premise of swapping character roles, and adding original content, to create new scenarios.

Undertale: Bits and Pieces is a mod of Undertale featuring completely overhauled graphics, new areas, new enemies and remixed music, as well as backporting content from its successor Deltarune

PurrSum

Undertale: Kindred Spirits is an Undertale fangame that tells the story of Batty and Mel, who possess the purple and blue souls respectively! Hiding from the Underground's Royal Guard, their journey takes many twists and turns, ultimately challenging their partnership along with whether the food is actually good - down here in the underground.

Avranik

A fanmade continuation of the Undertale genocide route, featuring a boss battle against Chara.

Soup Taels

Undertale: True Genocide is an Undertale fan-made game that takes place at the end of your genocide route in the original Undertale. True Genocide is a more story-driven fangame than your typical "press fight button to win" with you having to strategically ACT your way out of battles.

Angel's Lullaby takes place during the game's opening introduction, back during the Human and Monster War. Expanding on the lore, meta narrative and core themes of the original games, Angel's aims to enrich the Undertale world by mixing both the old and new. Combining both an open-world and linear story-line, Angel's is an ambitious fangame with a large story to tell. There's three main "Acts," each with it's own main area that follows a story.

In a game where anything can exist... LEMON SANS CHOOSES TO NOT.

An Undertale fangame in which Chara and their allies must defeat an entity known as ClickGaster who's main goal is to destroy their universe following the unintended destruction of his own.

Take on the role of a small human, as you explore an all new dynamic reimaging of the hit classic game UNDERTALE. Continue to decide the fate of monster kind's perception of humanity when faced with new unique surprises, and challenging obstacles. All in a world where no one has to die, again!

A 3 chapter Undertale fangame with Dream SMP in it

A fangame that uses the same roles as Storyshift, but uses them in a very different way. Project Reality will contain the same original characters you love, and some new ones as well...

Neofall is a RPG-PLATFORMER combo. You make friends, solve puzzles, beat bosses, and overcome your inner demons.

Avranik

In Wonderful Idea, the personalities of certain characters are amplified. For example, Toriel is more protective, Undyne is more determined and Papyrus even ends up joining the Royal Guard.

In this new part of Undertale's world, take control of the new protagonist Louis as he searches to learn the fate or whereabouts of someone he held dear. Alongside this, cave-dweller twin humans "Sunny" and Renée will be joining Louis on this journey.

In SPOOKYTALE, you follow the story of the young, rebellious Max, who’s on a search for their lost sibling. Their next big lead: a mysterious grave-yard. Throughout their adventure, you’ll get to meet new friends, visit old enemies, survive deadly japes, attend fancy balls, and explore a brand new world on the surface.