As a developer, you cannot prevent decompilation of a VM build. But you can raise the bar high enough that casual thieves move on. Use YYC. Obfuscate. Validate on the server.
The code was once someone’s creative labor. Decompile wisely, and never without consent.
| Defense Mechanism | How It Works | Can Decompiler Bypass It? | |-------------------|--------------|----------------------------| | | Converts GML to native x64/ARM assembly | ❌ No (practically impossible to revert to GML) | | Obfuscation (e.g., GM Obfuscator ) | Renames all functions to a() , b() , adds junk code | ⚠️ Partial – Decompiler runs, but output is gibberish | | Anti-Decompiler Checks | Scans for debugger presence, checks file hash | ✅ Yes – Can be patched out of the executable | | Custom Bytecode | Modify the runner to use non-standard opcodes | ❌ Rare – Breaks compatibility, requires custom runner | | Resource Encryption | Encrypt sprites/code, decrypt at runtime | ✅ Yes – Key can be extracted from memory | gamemaker studio decompiler
| Tool | Target GMS Version | Status | Notes | |------|--------------------|--------|-------| | | GMS 1.x, GMS 2.3 | Active | The industry standard. Open source. Handles bytecode, sprites, data. | | QuickBMS + GameMaker scripts | GMS 1.4 | Abandoned | Extracts assets only, not full code. | | Altar.NET | GMS 2.3+ | In development | Focuses on modern GMS 2.3+ file formats. | | GM Decompiler (by egofree) | GMS 1.4 | Dead | Old Windows tool, often flagged as malware by antivirus. |
GameMaker Studio 2 (and 1.x) has two primary export targets: As a developer, you cannot prevent decompilation of
If you are a developer looking to prevent people from snooping in your code, here are the industry standards:
GameMaker Studio decompilation is a technical reality rooted in the choice between VM convenience and YYC security. For every malicious pirate using decompilation to steal a $5 indie game, there is a modder preserving a classic or a student learning game internals. Obfuscate
Attempting to identify object structures, variable names (if not stripped), and script relationships to recreate a project that can be opened in the GMS IDE. Notable Tools and Resources
Decompilers scan these files, locate the bytecode signature, and feed it into a lookup table.
This compiles your GML directly into C++ , then uses a standard compiler (like GCC or MSVC) to turn that into native machine code. Result: Very hard to decompile back to GML.
Most decompilers work by targeting the data.win (Windows) or game.ios (Mac) files found in a game's installation folder. For legacy tools like the GM8.1 Decompiler , users typically drag the executable directly onto the tool icon to begin the process. Export Licences Pricing | GameMaker Get