Nope, it's the retail version
I really like Half-Life, that's why I bought it.
That error was produced by me . I've been messing a lot with cfg files, and I think I screwed up something
I finally found the solution to it. I had to edit the autoexec.cfg file, somehow it was "damaged". That's why it didn't work. I followed a guide to create a new one, and everything works fine now. Pheewww!!