...mods don't require source code. They're just mods. Trust us - there's no source. You're not going to see HalfLife unless someone gets Valve themselves to port it.
They did release some source code. I modify it and compile the hl.dll and client.dll binaries all the time. It's in c++, here is an example from cbase.cpp (from the SDK). Please see my post previous to yours.
Of course some mods are not "just mods". Sven Coop has new monsters, weapons, physics, sound system, etc. All of which required source code modifications (extensive ones too). We have tons of new files, not just mods to the existing ones. So I'm sorry, but I can't really trust you when you say "They're just mods. Trust us - there's no source" as that is clearly inaccurate. Download the SDK if you don't believe me (a number of sites has it hosted). It's really hard not to be snarky here when people make statements that are inaccurate while thinking they are the ones in the know. To correct someone else and be clearly wrong.
That being said, I already said the SDK was not enough for a port. He probably has the knowledge that the SDK is source code, just not that it isn't enough for a port. Hence why he probably doesn't listen to anyone who said that no code was released. Why would he trust anything else they said, if people already were wrong.
Also, see this pic if you want to see the code files on my HD:
CODE
img7.imageshack.us/img7/4543/hl1sdkfilese.jpg
CODE
/***
*
* Copyright (c) 1999, 2000 Valve LLC. All rights reserved.
*
* This product contains software technology licensed from Id
* Software, Inc. ("Id Technology"). Id Technology (c) 1996 Id Software, Inc.
* All Rights Reserved.
*
* Use, distribution, and modification of this source code and/or resulting
* object code is restricted to non-commercial enhancements to products from
* Valve LLC. All other use, distribution, or modification is prohibited
* without written permission from Valve LLC.
*
****/
#include "extdll.h"
#include "util.h"
#include "cbase.h"
#include "saverestore.h"
#include "client.h"
#include "decals.h"
#include "gamerules.h"
#include "game.h"
#include "functank.h"
extern "C" void PM_Move ( struct playermove_s *ppmove, int server );
extern "C" void PM_Init ( struct playermove_s *ppmove );
extern "C" char PM_FindTextureType( char *name );
void EntvarsKeyvalue( entvars_t *pev, KeyValueData *pkvd );
...