Team Undertale Yellow

Welcome to Undertale Yellow. In this fan made prequel to the RPG Undertale, you control a human who falls underground into the world of monsters... but will you make it out alive? Grab your cowboy hat and your gun and take the place of Undertale’s Yellow soul in their journey through the Underground on an original adventure.

RynoGG

A Deltarune fangame. Kris and Susie suddenly wake up on a flower bed in the world of Undertale. They, along with Noelle, must travel between different worlds to make their way back home.

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

Depa31

A co-op mod of Undertale, with this mod you will be able to play the entire game with two players.

Goinks

The first UNDERTALE fangame TO BE GOOD.

RickyG

Dontforget Connected is an online multiplayer Undertale/Deltarune fan-game with MMORPG-style gameplay. It features a new underground to explore, over 50 playable characters, new battle mechanics, and much more!

Underverse Battles is a multiplayer turn-based fighting game using the Undertale mechanics. Select your character and fight against other players. Dodge enemy attacks, choose your attacks carefully and win the fight.

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.

Team Colossus

Welcome to Underfell, an alternate universe of Undertale where the various monsters in the underground are vicious, where the law Kill or be Killed was firmly established. Never has the monster race been so divided before, gangs, mobs, a once united kingdom has now fallen and erupted into pure chaos. Can you survive the horrors of the underground?

Sad Bread

a fan-made sequel to the Spamton Neo fight.

Team Furenzu

Welcome to JAPARITALE, a crossover fan-game between the 2017 anime "Kemono Friends" and the hit RPG "UNDERTALE". One day, a human named KABAN, a long-lost child of the Park, randomly shows up in the Savannah Area. Fallen by a few vines on her path, she realizes the importance of dangers set afoot in this foreign land.

Noelle: Lost Soul is a DELTARUNE fangame set during an alternative ending of the Chapter 2's Weird Route.