valvesoftware/proton

Proton is a compatibility layer developed by Valve (the company behind Steam) that allows Windows-only video games to run on Linux. For a long time, most commercial games were built exclusively for Windows, which left Linux users with a much smaller library of playable titles. Proton bridges that gap by translating the Windows-specific instructions and system calls that a game makes into their Linux equivalents, in real time, as the game runs. The core technology it builds on is Wine, an open-source project that has been translating Windows software calls to Linux for decades. Proton extends Wine with additional components: notably DXVK and VKD3D-Proton, which translate DirectX (Windows's graphics API) calls into Vulkan (a cross-platform, high-performance graphics API). This is what allows graphically demanding 3D games to run efficiently on Linux, whereas older approaches often caused poor performance. Most Steam users on Linux never interact with this repository directly, Steam automatically downloads and uses Proton in the background when you launch a Windows game via Steam Play. This source code is published so that advanced users and developers can build custom versions of Proton: for example, to experiment with a newer version of Wine for a specific game, or to apply patches that haven't made it into the official release yet. Community-maintained forks like Proton-GE are built from this same codebase. You would use this repo if you are a Linux user interested in game compatibility research, or a developer who wants to contribute fixes. The project is primarily written in C++ and Shell scripts, built inside Docker or Podman containers to ensure a consistent build environment.