For multiplayer or competitive games, keep critical logic, player data, and anti-cheat checks on a secure external server rather than relying on client-side GML code.
The legal landscape is clear. The explicitly forbids decompiling, disassembling, or reverse-engineering any part of the software or games created with it. As one official GameMaker forum post bluntly states, "discussing reverse engineering like what you're asking is prohibited, and any attempt at decompiling violates the TOS". YoYo Games even closes forum threads that discuss decompilation to maintain compliance.
Modern compilers optimize code in ways that make the reconstructed logic look like "spaghetti code" to human eyes. Protecting Your Project If you are a developer worried about decompilation: gamemaker studio 2 decompiler
The IDE translates your GameMaker Language (GML) code into intermediate bytecode. This bytecode is then packaged into a data file (usually named data.win on Windows, or embedded inside the executable).
The existence of decompilers has naturally led developers to seek ways to protect their work. For older versions of GameMaker (pre-Studio), developers used obfuscators and anti-decompiler tools, often by simply packing the executable with a tool like UPX. For multiplayer or competitive games, keep critical logic,
This removes the interpretation layer, making the game run significantly faster.
Most GameMaker decompilers target VM builds. Because the data.win file contains structured bytecode and complete asset metadata, a decompiler can easily parse it. A VM decompiler performs the following steps: As one official GameMaker forum post bluntly states,
When a decompiler targets a GameMaker VM export, it parses the data.win file (or equivalent) and attempts to reconstruct the project structure. A successful decompilation usually yields: