One nice thing about Steam (back then, maybe still now?) was after the mod status left.
One copy of the Half Life box set (with Blue Shift, Opposing Forces, etc) could basically become as many copies as the whole thing.
I turned that one box set into several Steam accounts for my friends/I to share. Each 'mod' (turned game) basically granted a new Half Life license and cloned the derivatives
There was also a separate release of counterstrike called condition zero that included a single player campaign and a tweaked version of counterstrike multiplayer.
That was not included as part of that bundle.. but if you used the dedicated server tool to download the czero mod and copied it to your halflife folder you could play both the single player and multiplayer version on steam
This was how my brother played it. He was too dumb to know the difference because the box art literally looked like CS’s splash screen. CS != CZ but nevertheless, a steam account was a steam account, and technically CZ was HL so he downloaded CS off FilePlanet and was getting destroyed by me and my friends for weeks until he learned the strafe-run hack.
You get a special badge now too. I waited a month or 2 from release to install Steam because I only cared about Half-Life 2 and that was the first game from Valve that required Steam. You didn't even get a CD in the box, just a Steam redemption code.
One copy of the Half Life box set (with Blue Shift, Opposing Forces, etc) could basically become as many copies as the whole thing.
I turned that one box set into several Steam accounts for my friends/I to share. Each 'mod' (turned game) basically granted a new Half Life license and cloned the derivatives