The U3 SDK is the source code for Unturned, a free open-world zombie survival sandbox game.
Unturned is built as an open-world sandbox where players survive in a zombie-infested environment. The game provides a foundation for exploration, resource gathering, crafting, and combat within procedurally-generated or hand-crafted maps. By releasing the source code, the project enables developers and modders to understand the game's architecture, extend its functionality, and create custom content within the Unturned ecosystem.
This repository is suited for developers interested in studying how a large-scale multiplayer sandbox game is structured, those who want to contribute improvements to Unturned itself, and modders seeking to create custom gameplay experiences. The open-source nature means anyone can inspect the codebase, propose changes, and build upon the existing foundation. It works best for people already invested in the Unturned community or those learning from a complete, production-grade game implementation written in C#.
The project shows consistent development activity with regular commits addressing bug fixes, gameplay balance, and feature additions. Pull requests are reviewed and merged steadily, indicating an active maintenance cycle. The codebase receives updates that span multiple systems including networking, world generation, and player mechanics, demonstrating ongoing work across the full stack rather than isolated areas.
