UNDERTALE WORLD
by MoCurizZzx
Undertale World, a NeoForge world generation mod for 1.21.1, adds a hidden Underground dimension reached through a portal inside a small hill in the Overworld.
What it does
The mod adds a dimensional exploration area based on the Undertale setting. To reach it, a player finds a small hill in the Overworld with a bedrock portal hidden inside, then activates the portal with a Magic Stone. The stone is crafted from diamonds, bottles o enchanting and three emeralds. The first release includes two new biomes, several new materials, four generated structures and a boss challenge based on Undyne.
Undertale World requires Curios API as a dependency. Installation covers the server and each player's game. The source code is published under the MIT License and is open source. Files cover 1.21.1, with the latest being the beta released on 2026-05-01. The first file appeared on 2026-04-24. The author states that part of the code was produced with AI assistance and that development continues in MCreator, with plans to combine it with IntelliJ IDEA before a full official release.
Key features
Hidden Underground dimension
A portal inside a small Overworld hill leads to an Underground world with its own biomes and structures.
Magic Stone activation
The portal opens after a Magic Stone is used on it, and the stone is crafted from diamonds, bottles o enchanting and emeralds.
New equipment and materials
Several new materials and equipment items are added alongside the dimension's content.
Undyne boss challenge
A boss encounter modeled on Undyne serves as the main challenge in the new area.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
How it compares
FxUndertale is also open source under the MIT License, with client and server files for NeoForge on 1.21.1, so it covers the same version as Undertale World. MossFan Deltarune weapons is a client and server mod for NeoForge on 1.21.1 that is not open source and is released under All rights reserved. Undercraft is published for NeoForge on 1.21.8, and Undertale Stuff for NeoForge on 1.20.4, both under the MIT License and both not open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| UNDERTALE WORLD | NeoForge | 1.21.1 | Client and server | 2026-05-01 |
| FxUndertale | NeoForge | 1.21.1 | Client and server | 2026-05-02 |
| MossFan Deltarune weapons | NeoForge | 1.21.1 | Client and server | 2026-07-18 |
| Undercraft | NeoForge | 1.21.8 | Client and server | 2026-03-20 |
| Undertale Stuff | NeoForge | 1.20.4 | Client and server | 2024-06-18 |
Questions
Does Undertale World need Curios API?
Does the server need Undertale World?
Which Minecraft version does Undertale World support?
In the catalog
UNDERTALE WORLD is one of 8,515 World generation mods on ModsFinder, and one of 4,175 World generation mods for NeoForge. 32,366 mods support Minecraft 1.21.1.
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What the author says
(Mcreator production) this is a dimensional exploration mod for Undertale. Although my personal technical skills are limited, I strive to recreate and expand the world of Undertale in Minecraft in my own way. Find a small hill in the Overworld. You need to use a Magic Stone — crafted from diamonds, bottles o'…
Official listing
- Modrinth page
- modrinth.com/mod/undertale-world
- Owner
- MoCurizZzx
- Published
- 2026-04-24
- Updated on Modrinth
- 2026-05-01
- Facts verified
- 2026-10-15