alt Hacker NewsYeah that's just the game logic which has been out since 1999. The rendering/networking/animation/UI/sound etc stuff is all still closed source (though apparently there is a leak from a Counter-Strike Online developer circulating among private hands - some code was contributed to Xash3D which perfectly implemented a non-trivial scripting system which was suspicious enough that it was removed).
Isn't that because a lot of GoldSrc was idTech-derived enough that the legality of open sourcing it is trapped in contract law limbo? Even though those years of the idTech engine itself are now also open source, the contracts at the time did not plan for that and it is likely at this point that solving those contracts would be a 3-way legal question between Microsoft (ActiVision because of Vivendi/Sierra, Half-Life's original publisher), Microsoft (Bethesda because of inheriting idTech), and Valve, with the obviously problem in the way of that Valve and Microsoft have a complex history and aren't likely to want to get into a legal discussion if they can help it.
I seem to recall a fan project trying to take idTech's open source and recreate GoldSrc's fork from it by trying to reverse engineer from the parts of Half Life that are open source but not having much luck because the divergence was strong enough in some places to be somewhat impenetrable without some other Rosetta Stone.