Deltamod Community

Your mods. Your worlds. One launcher.
A community-built mod manager for DELTARUNE, UNDERTALE,
and other supported GameMaker games.

Download Deltamod  •  Getting started  •  Supported games  •  Get help

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What is Deltamod?

Deltamod Community helps you install, organize, and launch mods without manually moving game files around for every setup.

You can:

• browse compatible mods from GameBanana, ModDB, and Nexus Mods;
• import mod archives you already downloaded;
• keep different mod setups separated with installations, profiles, and collections;
• apply supported GameMaker patches, including UndertaleModTool .csx patches on compatible platforms;
• switch between eight interface languages and community themes.

If you only want to play with mods, you do not need Node.js, Rust, Git, or any development tools.

Download and install

Get the newest stable build from the official GitHub release page:

Choose the installer for your operating system. Windows and macOS packages are currently unsigned because this community project does not have paid platform-signing credentials.

Important

Download Deltamod only from this repository's official Releases page. Each stable release includes SHA256SUMS.txt so you can verify your download before installing it. Deltamod does not currently update itself automatically, so install newer releases manually when they are published.

Windows

1. Download the Windows setup .exe from the latest release.
2. Check its SHA-256 hash against SHA256SUMS.txt on the release page.
3. Run the installer and open Deltamod Community.

Windows may show an Unknown publisher warning because the installer is not code-signed. Verify that you downloaded it from the official release and that the checksum matches before continuing.

macOS

1. Download the DMG matching your Mac: Apple Silicon or Intel.
2. Open the DMG and move Deltamod Community to Applications.
3. Launch it from Applications.

The app is not currently notarized. After verifying the release checksum, macOS may require you to allow the app from System Settings → Privacy & Security.

Not sure which Mac you have? Open Apple menu → About This Mac and check whether it shows an Apple chip or an Intel processor.

Linux

The official Linux release is a Debian package (.deb). Install it with your graphical package manager or from a terminal:

sudo apt install ./deltamod-community-*.deb

Linux support is currently experimental. The official package targets x64 Debian-based systems.

Tip

Files such as .blockmap, .yml, source bundles, or GitHub's automatic source archives are not normal installers. Use the .exe, .dmg, or .deb intended for your platform.

Getting started

A normal first setup looks like this:

1. Open Deltamod Community.
2. Add or select your game installation. Deltamod can keep multiple installations separate.
3. Choose a mod. Browse a supported catalogue or import a local archive.
4. Install the mod. Deltamod prepares the package and adds it to your mod setup.
5. Choose which mods you want active. Keep separate setups when different mods or game versions should not mix.
6. Patch and launch the game from Deltamod.

Individual mods can require a specific game version or conflict with other mods. Read the mod author's instructions before installing it.

Where can I get mods?

Source	How it works
GameBanana	Browse supported catalogue entries directly in Deltamod.
ModDB	Browse supported listings and open compatible downloads.
Nexus Mods	Sign in from Options → Nexus Mods to browse Nexus content.
Local archive	Import a compatible mod archive you already downloaded.

Nexus Mods accounts

Nexus Mods sign-in uses your browser and returns you to Deltamod after authorization.

• Premium users: compatible archives can be downloaded through the Nexus Mods API.
• Non-Premium users: Nexus may require you to confirm the download on its website; once downloaded, import the archive into Deltamod.
• No Nexus account: GameBanana, ModDB, and local imports continue to work normally.

Deltamod does not ask you to paste a Nexus password or client secret into the app.

Supported games

Game	Support
DELTARUNE	✅
DELTARUNE Demo	✅
DELTARUNE Demo (LTS)	✅
UNDERTALE	✅
Undertale Yellow	✅
Pizza Tower	✅

Support for a game does not mean every mod works with every version of that game. Check the mod's own compatibility notes first.

Platform support

Platform	Status	Notes
Windows x64	Stable	Recommended platform.
Linux x64	Experimental	Official release is a .deb package.
macOS Apple Silicon	Experimental	Native app; UndertaleModTool .csx patches are unavailable.
macOS Intel	Experimental	Native app with .csx patch support.
Wine / CrossOver	Unofficial	May work, but is not an official release target.

UndertaleModTool .csx patches are supported on Windows x64, Linux x64, and Intel Macs. Upstream does not currently provide the required CLI binary for Apple Silicon.

Before installing mods

Modding changes how a game runs, so a few precautions are worth taking:

• Back up important saves and game files before experimenting with mods.
• Use mods from authors and sources you trust.
• Check that a mod supports your exact game version.
• Avoid combining mods unless their authors say they are compatible.
• Treat .csx patches as executable mod scripts and review their source/trustworthiness before allowing them to run.
• Do not upload copyrighted game files, passwords, tokens, or other private data when asking for support.

Deltamod includes validation, staging, and restore mechanisms around supported patch operations, but those safeguards are not a replacement for your own backup.

See it in action

Manage your setups

_{Move between your patch list, installed mods, game installations, and collections.}

Discover and install mods

_{Browse the Mod Shop, preview content, and follow download and import progress. Catalogue entries shown here use local demo data.}

Personalize the app

_{Choose a visual theme and switch between eight interface languages.}

Troubleshooting

The game or mod does not work

• Confirm the mod supports your exact game version.
• Try the mod by itself in a separate setup to rule out conflicts.
• Check the mod author's installation notes and known issues.
• If the problem is caused only by one mod, report it to that mod's author first.

Windows says the publisher is unknown

The Windows build is currently unsigned. Download it only from the official release page and verify its SHA-256 checksum against SHA256SUMS.txt before deciding whether to run it.

macOS blocks the app

The macOS build is currently unsigned and not notarized. Verify the release checksum first, then use System Settings → Privacy & Security if macOS requires manual approval.

Nexus download does not start

If you use a Non-Premium Nexus Mods account, Nexus may require the download to be confirmed on its website. Download the archive there, then import it into Deltamod.

For account authorization problems, try signing in again from Options → Nexus Mods.

I still need help

Read SUPPORT.md or open an issue.

When reporting a problem, include your Deltamod version, operating system, game/version, mod/source, reproduction steps, and sanitized logs or screenshots when useful.

For security vulnerabilities, do not open a public issue. Follow SECURITY.md and use GitHub private vulnerability reporting.

About Deltamod Community

Deltamod Community is an independent community fork of Deltamod. It was created in response to concerns about censorship in the original repository and aims to preserve freedom of creative expression while respecting applicable laws, platform rules, and community safety.

This project is independent from the original Deltamod project and is not affiliated with or endorsed by Toby Fox.

For contributors and developers

You do not need this section to install or use Deltamod.

Development requires Node.js 22. Tauri builds additionally require the platform prerequisites for Tauri development.

git clone https://github.com/cmdr-chara/deltamod.git
cd deltamod
npm ci
npm run dev

Common checks:

npm test
npm run typecheck
npm run security:audit

Build commands:

Target	Command
Windows	npm run build-windows
Linux	npm run build-linux
macOS	npm run build-macos
Tauri	npm run build:tauri

Technical details: Nexus integration

Deltamod uses OAuth 2.0 Authorization Code with PKCE S256 for Nexus Mods sign-in. The registered loopback callback is fixed at http://127.0.0.1:52817/callback; the client never falls back to a dynamic port.

Nexus catalogue browsing uses a bounded result page of 50 items and fetches only the requested page. Nexus quota handling honors Retry-After and quota reset metadata so requests can pause and retry instead of repeatedly hitting the API while limited.

Patching uses G3MTool and the UndertaleModTool CLI. For contribution, release, and third-party details, see:

• CONTRIBUTING.md
• RELEASE-GATE.md
• THIRD_PARTY_NOTICES.md
• NOTICE.md

License

Deltamod Community is licensed under the European Union Public Licence 1.2. Attribution and bundled third-party software are documented in NOTICE.md and THIRD_PARTY_NOTICES.md.

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Made with ❤️ by the Deltamod community.
_{An independent fan project. Not affiliated with or endorsed by Toby Fox.}