Unity is a cross-platform game engine developed by Unity Technologies, and is the game engine used by 7 Days to Die.
Modders interested in adding custom blocks, sounds, and entities into the game would need to use Unity to package up their new content. Unity exports packages in Unity3D files using an Asset Bundle Export script.
Assembling the Tool Chain
In order to get started using Unity and adding items into the game, you must download and install the following packages.
Alpha 16 - Unity version 5.3.8p Download From Unity
Alpha 17 - Unity Version 2018.2.x Download From Unity
Alpha 18 - Unity Version 2019.1.x Download From Unity
Unity Asset Bundle Export Script
To add support to Unity to allow it to export Unity3d Asset bundles, a script must be downloaded and installed in unity.
The script may be found here: Export Asset Bundle Script. Copy the contents of the script into a file called ExportAssetBundles.cs.