This is a .DLL file which adds .ASI file loading capability to (all) GoldSrc games.
Well, I'm unsure about ALL games support. So far I've tested Sven Co-op and the original game, it works there very well.
Just copy the repository onto your drive, open up StarLoader\StarLoader.sln file with MSVS 2015/2017/2019/2022 and hit Ctrl+Shift+B.
The artifact will be in StarLoader\Debug or StarLoader\Release folder.
Rename StarLoader.dll into hid.dll and follow HOW TO INSTALL
Either follow HOW TO BUILD to build an artifact, or download one from Releases.
Drop the hid.dll file into game ROOT folder (e.g. C:\Program Files (x86)\Steam\steamapps\common\Sven Co-op\) and launch the game at least once.
A folder named starloader will appear in the game ROOT folder. Drop any needed .ASI plugins there, they'll be loaded upon game start/restart.