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The most complete tool for modding, decompiling and unpacking Undertale (and other Game Maker: Studio games!)
$ winget install --id krzys-h.UndertaleModTool --exact --version 0.9.0.0Run in Command Prompt, PowerShell, or Windows Terminal. Prompts for any agreements.
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The most complete tool for modding, decompiling and unpacking Undertale (and other GameMaker games!)
Main Features:
- Can read every single byte from the data file for latest versions of Undertale, Deltarune, and most other GameMaker games, and then recreate a byte-for-byte exact copy from the decoded data.
- Properly handles all of the pointers in the file so that if you add/remove stuff, make things longer/shorter, move them around, etc., the file format won't break.
- An editor which lets you change (almost) every single value, including unknown ones.
- Includes a simple room/level editor.
- Allows for GML VM code editing. This means you can add any custom code to a game, either using the built-in GML compiler or GML assembly. (YYC is not supported for this.)
- High-level GML decompiler and compiler. Supports a large range of GameMaker versions, and most important GML features (still missing a few).
- Support for running scripts that automatically modify your data file (or perform other nefarious tasks). This can be used for mod distribution, aside from other methods such as file patches/project systems.
- All core functionality extracted into a library for use in external tools.
- Can generate a .yydebug file for the GM:S debugger so that you can edit variables live! (see here)
- Automatic file associations for all GameMaker related data files. This is opt-in at the first boot of the tool, and can also be disabled by having a dna.txt file next to the executable.
| Architecture | Type | Scope | Install | Download |
|---|---|---|---|---|
| neutral | ZIP archive | - | Direct |
Copy a command tailored to that specific architecture, type, and scope - useful when winget would otherwise pick a different default.
No known CVEs for UndertaleModTool.
Coverage is best-effort and depends on a winget package mapping to an NVD CPE entry. Absence here is not a guarantee of safety.
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More from krzys-h or browse decompiler, deltarune, editor.