You can find the latest stable version of the engine on the official Xash3D GitHub Releases page . Version 0.19.2 is a widely recognized stable build.
Most updates come as a .zip or .apk file. To run Half-Life, you typically need to copy the valve folder from your purchased Steam copy into a folder named xash on your device. Download xash3d update link here redme zip
Verified builds are also available on SourceForge for those who prefer it. Releases · FWGS/xash3d-fwgs - GitHub You can find the latest stable version of