About this project

OpenXRay is a fan-maintained, open-source fork of the X-Ray Engine originally developed by GSC Game World for the S.T.A.L.K.E.R. franchise. The project targets three titles—Call of Pripyat 1.6.02, Clear Sky 1.5.10, and the Call of Chernobyl 1.4.22 mod—with Shadow of Chernobyl support still in progress. Key improvements over the upstream engine include native 64-bit builds, substantial FPS and stability gains, fixes for long-standing vanilla bugs, and a growing set of optional graphics and gameplay enhancements that can be toggled by modders or players. The engine runs on Windows, Linux, macOS, *BSD, and exotic architectures such as ARM, ARM64, Elbrus 2000 (E2K), and PPC64LE. An OpenGL renderer replaces the original DirectX 9/10/11 pipeline, and a Vulkan/DX12 backend is under active development. Build instructions for all supported platforms are documented in the project wiki, and CI pipelines validate each pull request. For mod authors, OpenXRay exposes a frame/render graph, extended Lua scripting APIs, new debugging tooling, and a refreshed SDK, enabling modern graphics techniques (e.g., PBR, volumetric lighting) without breaking existing gamedata archives. The project maintains a "vanilla-first" philosophy: new features are opt-in and original assets remain loadable unchanged. Community coordination happens on Discord, GitHub Issues, and a VK group. Contributions are welcomed—good-first-issue and help-wanted labels guide newcomers—and financial support is accepted via GitHub Sponsors, Patreon, Open Collective, and Boosty. The codebase is licensed under the original X-Ray terms; users must own a legal copy of the supported S.T.A.L.K.E.R. games to play.