The search for a GameMaker Studio 2 (GMS2) decompiler often stems from a common developer nightmare: losing a project due to a corrupted hard drive, a failed cloud sync, or an accidental deletion without a backup. If you find yourself holding a compiled executable of your own game but lacking the source code, a decompiler is your last line of defense.
Here is everything you need to know about finding, installing, and using a GMS2 decompiler for free. What is a GameMaker Studio 2 Decompiler?
A decompiler is a tool that takes a compiled game file (like an .exe for Windows) and attempts to reverse-engineer it back into a readable project format (.yyp). While GameMaker games are compiled into bytecode, tools like UndertaleModTool can read this data and extract: GML Scripts: The logic and code of your objects. Sprites and Strips: The visual assets and animations. Rooms and Layers: The level design layouts. Shaders and Fonts: Technical rendering assets. The Best Free Tool: UndertaleModTool
Despite the name, UndertaleModTool (UTMT) is the industry standard for decompiling and modding almost any game made with GameMaker Studio 2. It is open-source, free, and actively maintained on GitHub. How to Install UndertaleModTool
Visit the Official GitHub: Navigate to the "UndertaleModTool" repository. Always download from GitHub to avoid malware found on third-party "free download" sites.
Download the Latest Release: Go to the "Releases" section on the right sidebar and download the .zip file for the latest stable version.
Extract the Files: Unzip the folder to a dedicated location on your PC.
Install Dependencies: Ensure you have the latest .NET Core Runtime installed, as the tool requires it to run on Windows. Step-by-Step Recovery Guide
Once you have the tool installed, follow these steps to recover your project files: 1. Load the Game Data
Open UndertaleModTool.exe. Go to File > Open and navigate to your compiled game's folder. You are looking for a file named data.win. In some exports, this might be embedded in the .exe, but for most GMS2 games, it sits in the same directory. 2. Browse the Assets
Once loaded, you will see a list of categories on the left (Scripts, Sprites, Objects). You can double-click any entry to view the raw GML code or export specific images. 3. Full Project Export To turn the compiled data back into a GMS2 project: Go to the Scripts menu at the top. game maker studio 2 decompiler free install
Select ResourceBundle.cs or a similar "Export to Project" script. Choose a destination folder.
The tool will recreate the folder structure needed for GameMaker to recognize it as a project. Important Limitations
While decompilers are powerful, they are rarely perfect. Keep these realities in mind:
Variable Names: Local variables (like var _temp) are often lost during compilation. The decompiler might rename them to generic strings like local_1.
Comments: All code comments are stripped during compilation. You will have to re-document your recovered logic.
Version Mismatch: If the game was made with a much older or significantly newer version of GMS2 than the decompiler supports, some scripts may fail to export correctly. Ethical and Legal Note
Decompilers should be used for educational purposes or data recovery of your own work. Using these tools to steal assets or code from other developers is a violation of copyright law and the GameMaker EULA. Always respect the hard work of the indie community.
💡 Pro-Tip: To avoid ever needing a decompiler again, set up a free GitHub or Bitbucket account and use Git for version control. It is the only 100% reliable way to protect your source code.
If you'd like to know more about setting up Git for GameMaker or need help fixing specific export errors in the tool, just let me know!
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 The search for a GameMaker Studio 2 (GMS2)
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.
Load File: Navigate to your game's installation folder and select the data.win file.
Decompiling GameMaker Studio 2 (GMS2) games is technically difficult and often restricted by legal agreements. Unlike older versions (like GM8), modern GMS2 games are compiled into complex bytecode or machine code (via YYC), making it impossible to "revert" them into a standard project file with a single click. Available Tools and Projects
While no official "decompiler" exists, the community uses specialized tools to inspect game data or extract assets:
UndertaleModTool: The most popular community tool for modern GMS2 games. It allows users to view and modify the data.win files common in GMS games. It is frequently used for modding popular titles like Undertale and Deltarune.
Altar.NET (GameMaker-Studio-Decompiler): A GitHub project designed to export parts of a data.win file and disassemble code, though it is primarily for advanced users and developers. Outdated (for GMS1
Asset Extractors: Tools like the GMS2-PNG-Decompiler are used specifically to dump visual assets (sprites and backgrounds) rather than the underlying code.
Legacy Decompilers: Older tools like gm81decompiler or GM Decompiler v2.1 only work for legacy versions (GM8.1 and earlier) and are not compatible with GMS2. Technical and Legal Realities
WastedMeerkat/gm81decompiler: GameMaker 8.1 Decompiler - GitHub
I understand you're looking for information about decompiling GameMaker Studio 2 games, but I need to provide an important clarification upfront:
There is no legitimate, free, ready-to-install GMS2 decompiler available publicly. Most tools claiming to be GMS2 decompilers are either:
Copy the game files to a separate folder. Never work on the original.
Believe it or not, many indie developers will share old project files if you email them politely. Explain you are a student learning GML. You would be surprised how generous the GameMaker community is.
When you create a game in GameMaker Studio 2, you write source code (GML – GameMaker Language). This is human-readable, organized into scripts, objects, and events.
When you export your game (to Windows, macOS, HTML5, etc.), the compiler translates that human-readable code into machine code or bytecode—something the computer can run quickly, but that looks like gibberish to a human.
A decompiler attempts to reverse this process. It takes the compiled executable and tries to recreate something resembling the original source code.
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All classes offered as standard courses, or we can work with you to address your organization's specific needs, including via the combination and/or customization of our training offerings.
