When modding Unity games with MelonLoader, understanding the difference between Mods and Plugins is essential. Placing files in the wrong folder is one of the most common reasons mods fail to load or cause startup errors. This guide explains the MelonLoader folder structure, the role of each directory, and exactly where mod and plugin files should be placed.
This guide assumes MelonLoader has already been installed and the game has been launched at least once.
MelonLoader Directory Structure Explained
After installing MelonLoader and launching the game for the first time, several folders are automatically created inside the main game installation directory. This is the same directory that contains the game executable file.
Example Game Root Directory
C:\Program Files\GameName\
GameName.exe
GameName_Data
MelonLoader
Mods
Plugins
UserData
The two folders most users interact with are Mods and Plugins.
The Mods Folder
What the Mods Folder Is Used For
The Mods folder is intended for standard gameplay mods that directly change or extend the game itself. These mods interact with the game’s internal systems, such as adding new content, modifying mechanics, or changing the user interface.
Mods are loaded after the game and MelonLoader have completed most of their initialization.
What Belongs in the Mods Folder
- Game specific feature mods
- Content additions such as items, towers, characters, or maps
- Gameplay changes such as balance adjustments or mechanics edits
File Type
- Usually a single .dll file per mod
Correct Placement
Place mod .dll files directly inside the Mods folder.
Example Path
C:\Program Files\GameName\Mods\MyFirstMod.dll
The Plugins Folder
What the Plugins Folder Is Used For
The Plugins folder is reserved for tools and frameworks that extend MelonLoader itself or provide shared functionality used by multiple mods. Plugins are loaded before mods and often before the game finishes initializing.
This early load order is important for tools that patch core systems or provide APIs.
Common Plugin Examples
- Modding frameworks and APIs
- Utility tools used by many mods
- Debug or inspection tools
- UI frameworks and patching libraries
File Type
- Usually a single .dll file per plugin
Correct Placement
Place plugin .dll files directly inside the Plugins folder.
Example Path
C:\Program Files\GameName\Plugins\UniversalFramework.dll
The UserData Folder
What the UserData Folder Is Used For
The UserData folder stores data generated or used by mods and plugins. It does not contain executable code. Instead, it holds configuration files, user settings, logs, and custom assets.
Keeping this data separate allows mods to be updated or removed without losing settings.
What Belongs in the UserData Folder
- Configuration files such as .cfg, .json, or .xml
- Mod specific save data or settings
- Custom assets loaded at runtime
- Log files generated by MelonLoader or mods
Placement Rules
Most files in UserData are created automatically. Manual placement is usually only required when a mod developer instructs you to add custom assets or configuration files.
Example Path
C:\Program Files\GameName\UserData\MyModConfig.cfg
How to Tell Whether a File Is a Mod or a Plugin
When downloading a .dll file, it is not always obvious which folder it belongs in. These guidelines can help.
Read the Mod Author’s Instructions
Mod creators almost always specify whether their file should go into the Mods or Plugins folder. This is the most reliable source of information.
Context Clues
If the file is described as:
- A dependency
- A framework
- A utility
- An API
It usually belongs in the Plugins folder.
If the file is described as:
- A gameplay feature
- A content mod
- A cheat or enhancement
- The main mod file
It usually belongs in the Mods folder.
Load Order Summary
Plugins
- Location: Plugins folder
- Load order: Loaded first
- Purpose: Extend MelonLoader or provide shared functionality
Mods
- Location: Mods folder
- Load order: Loaded after plugins
- Purpose: Modify or add game specific content
Common Mistakes to Avoid
- Placing plugin files inside the Mods folder
- Placing gameplay mods inside the Plugins folder
- Mixing Mono and Il2Cpp incompatible mods
- Renaming .dll files without instructions
- Installing mods before launching the game once with MelonLoader
Final Summary
MelonLoader separates mods and plugins to ensure proper load order and stability. Mods belong in the Mods folder and change gameplay or content. Plugins belong in the Plugins folder and provide shared tools or frameworks. Configuration files and custom data belong in the UserData folder. Placing files in the correct directory ensures mods load correctly and prevents common startup errors.
Official MelonLoader installer:
https://melonloader.pro/download-melonloader/
GitHub releases: https://github.com/LavaGang/MelonLoader/releases