Disclaimer: This article is for educational purposes only. Decompiling software without explicit permission from the copyright holder (the game developer) is a violation of the End User License Agreement (EULA) of GameMaker Studio 2 and constitutes software piracy or reverse engineering. This guide explains the technical landscape; you are responsible for your own legal compliance.
.yyp files).UndertaleModTool.zip (no installer)UndertaleModTool.exedata.win from game’s install folderGMS2’s IDE includes a debugger. While you cannot see another game’s code, you can study your own. Learn by rebuilding mechanics yourself.
There is no safe, reliable, or legal "one-click" decompiler for modern GameMaker Studio 2 games, especially those compiled with YYC. Attempting to download such tools from the open web puts your computer at high risk of infection.
The best advice: If you want to make games, download the free version of GameMaker Studio 2 directly from the official website. It is legal, safe, and the most effective way to learn how GameMaker projects are structured.
These tools will not recover original variable names, comments, or project structure – only bytecode and assets. Many modern GMS2 games use YYC compilation (C++), which is far harder to decompile.
If you’re trying to recover your own lost project, also check:
%localappdata%\GameMakerStudio2\Backups)While there is no official tool to turn a compiled GameMaker Studio 2 (GMS2) executable back into a project file, community-developed tools can help you extract assets or code for recovery purposes. Available Decompiler Options
True "decompilation"—reverting a game to a fully functional .yyp project—is not natively supported by GameMaker. However, you can use these tools to recover specific parts of a lost project:
UndertaleModTool: Widely considered the most effective tool for modern GameMaker games. It allows you to open the data.win file accompanying your .exe to view and extract GML scripts, sprites, and room data. Source: UndertaleModTool on GitHub game maker studio 2 decompiler free install
GMSD (GameMaker Studio Decompiler): A tool designed to export scripts and assets from the data.win file into a readable format. Source: lynn/GMSD on GitHub
GameMaker-Studio-Decompiler (Altar.NET): A command-line utility for exporting parts of a data.win file. Source: jeason1997/GameMaker-Studio-Decompiler Important Constraints
While there is no "official" free decompiler for GameMaker Studio 2 (GMS2), several community-driven tools exist that are free to install. The most widely used is UndertaleModTool, which is frequently updated and capable of reading GMS2 data files. Top Community Decompilers (Free) UndertaleModTool Modding GMS2 games and basic code recovery. Altar.NET Reading .win files via C#. GitHub GMSD (F#) Simple script extraction to text files. GitHub Review & Performance
Ease of Use: Most tools, especially UndertaleModTool, use a straightforward "File -> Open" interface for .win files.
Capabilities: These tools can typically extract sprites, sounds, and GML (GameMaker Language) code. However, they often cannot reconstruct a perfect .yyz project file that opens immediately in the GMS2 IDE without errors.
Limitations: Decompilation works best on games compiled with the standard VM (Virtual Machine). Games compiled with the YYC (YoYo Compiler) are significantly harder to decompile because they are converted to native C++ code. Installation Guide for UndertaleModTool
Download: Visit the Official Releases page and download the SingleFile.zip version.
Extract: Fully extract the ZIP folder to your desktop or a dedicated folder (do not run from inside the archive). Run: Open UndertaleModTool.exe. Disclaimer: This article is for educational purposes only
Load File: Navigate to your game's installation folder and select the data.win file.
While there is no "official" or built-in decompiler for GameMaker Studio 2
(GMS2), several community-led open-source tools exist that can extract assets and approximate source code from compiled games. These tools are primarily used for modding or recovering lost project files. Common GMS2 Decompilation Tools
The following free, open-source projects are frequently used by the community: UndertaleModTool
: The most widely used tool for modern GameMaker games. Despite its name, it works on many GMS2 games by opening the
file. It allows you to view and edit scripts, sprites, and other game data. GMSD (GameMaker Studio Decompiler) : An F#-based decompiler that takes a
file and attempts to write scripts to text files. Users must compile the source code themselves using Visual Studio
: A C#-based unpacker and decompiler specifically designed for GMS games that use the non-YYC (YoYo Compiler) export method. If you want to mod a GMS 2 game:
: A modern effort to rewrite classic GameMaker engines, which includes a decompiler for older file formats like Technical Limitations
: Compiling a game is a "one-way" process. Decompilers can only approximate the original logic; comments, original variable names (in some cases), and code structure are often lost or replaced with generic identifiers. YYC Compatibility : Games compiled with the YoYo Compiler (YYC)
are converted into machine code (C++), making them significantly harder to decompile compared to the standard VM (Virtual Machine) export. Legal and Ethical Considerations
In the United States and many other countries, circumventing copy protection is illegal under the Digital Millennium Copyright Act (DMCA). Most commercial GMS2 games have at least basic protection.
Even if a game has no explicit DRM, the source code is considered a copyrighted work. Decompiling without permission is typically a violation of the EULA (End User License Agreement) you accept when installing the game.
| Tool Name | Works with GMS2? | Free? | Risk Level | |-----------|----------------|-------|-------------| | GM Decompiler (classic) | No (GMS1 only) | Partially | Low (if from original source) | | UndertaleModTool | Partial (mostly assets) | Yes (open source) | Low (GitHub) | | GMS2 Decompiler (fake names) | Claim yes, but rarely | "Free install" | Extremely High | | Hex Rays / IDA Pro | No (not GML-specific) | No | N/A |
Current reality as of 2025–2026: There is no reliable, fully functional, free GMS2 decompiler that can perfectly restore original GML source code with variable names, comments, and exact object structures. The ones that exist are either for GMS1 or only extract sprites/sounds.
The most famous GMS2 decompiler is UndertaleModTool (UTMT). Ironically, it was created to mod Undertale, but it works on many GMS1.4 and GMS2 VM games.