ValveSoftware/Proton is a compatibility layer that enables Windows games to run on Linux via the Steam client. It integrates Wine, DXVK, vkd3d-proton, and other components to translate Windows API calls to Linux equivalents. The repository contains the build system (Makefile, Dockerfiles), the Steam client wrapper (lsteamclient) with auto-generated thunks for dozens of Steamworks SDK versions, the VR client wrapper (vrclient_x64) for OpenVR, and an OpenXR loader (wineopenxr). The codebase is heavily auto-generated from SDK headers, with manual implementations for complex interfaces. It is actively maintained by Valve and the community, with a focus on broad game compatibility. The architecture is a set of shared libraries loaded by Wine, not a standalone application.