ModTool

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ModTool makes it easy to add mod support to your game. It enables modders to use the Unity Editor to create scenes, prefabs and code and export them as mods for your game.
To make sure the modder's scripts or Assemblies will be compatible with the game, ModTool has a simple but powerful code validator, that lets you configure any number of requirements.
ModTool creates a custom unitypackage for each project, which includes everything to create and export mods.
Features
•Let modders use the Unity editor to create scenes, prefabs and code for your game
•Scripts and assemblies are fully supported
•Code validation
•Supports Windows, OS X, Linux and Android
•Mod conflict detection
•Automatic mod discovery
•Asynchronous discovery and loading of mods
See the documentation for more information about features, limitations and how to use ModTool.