wtf is u3-sdk?

This repository holds the source code for Unturned, a free open world zombie survival sandbox game. It is the software development kit that Unturned's own developers use to build and modify the game, made public so players and modders can look inside and create their own changes. To get it running, someone needs to download or clone the repository, then install Unity Hub, which is a launcher used to manage different versions of the Unity game engine. From there they install the specific Unity editor version the project needs. If they plan to actually change the code rather than just look at it, the README also suggests installing certain Visual Studio components for game development and desktop application work. Because the game's large art assets, sound files, and mod content are not stored directly in this repository, Steam needs to be running with Unturned itself already installed on the same machine, so the project can load those files from the existing game installation. Once everything is set up, the person opens the project in the Unity editor, loads a specific starting scene called GameStartup, and presses play to launch it. The README points to a few outside resources for anyone getting stuck or wanting to go further: a frequently asked questions page, a video walkthrough that demonstrates adding a heat seeking missile as an example of a code change, and the official modding documentation for Unturned. The project itself is written in C#, matching how games built with Unity are typically coded.