https://github.com/FWGS/hlsdk-portable/tree/decay-pc2

Rebased fan made Decay PC port on top of our hlsdk-portable tree, and also fixed a few bugs along the way.

Using this SDK tree means wider support for various operating systems, CPU architectures and game engines, and minor HL bug fixes, some of which are optional.

Thanks to Vyacheslav Dzhura for publishing original mod source code: https://github.com/hoaxer/Half-Life-Decay and to code.idtech.space for saving historic HLSDK versions, which made rebasing semi-automated. Took me a day ^^