Source 2004
Source 2004 is the original build of the Source engine that Half-Life 2, Half-Life: Source and Counter-Strike: Source shipped with. It was succeeded by the Source 2006 engine branch with the release of Half-Life 2: Episode One.
No current Valve titles hosted on Steam use this particular engine branch, as it is outdated.
Vampire: The Masquerade - Bloodlines still runs on a custom version of the engine, similar to the engine used in the Half-Life 2 Beta leak. However, it uses a proprietary texture format and BSP version 17, and support Bink videos.
SiN Episodes also likely used the last?[confirm] build of Source 2004, or possibly an early version of the Source 2006 branch previously used by 
Half-Life 2: Lost Coast, combined with Source 2004 code[confirm], which contains few commands related to the HDR Rendering which was non-functional ("mat_hdr_enabled").
Availability
Source code for this branch is no longer officially available. Most Valve games introduced with Source 2004 are now currently using Source 2013 Singleplayer or Source 2013 Multiplayer.
An archive of the 2004 SDK is available on GitHub.
Usage
The following games are still based on, or currently using Source 2004.
Valve
2005
Half-Life 2 (Xbox)
Third-Party
2004 Vampire: The Masquerade - Bloodlines (Beta version)2006 SiN Episodes
System Requirements
Minimum Specs :
- OS: Windows 98 / ME, 2000, XP or later
- CPU: 1.2 GHz
- RAM: 256 MB
- Nvidia GeForce FX 5700, ATI Radeon 9500 (with 128MB VRAM)
- Direct3D 9.0 compatible video card (with atleast DirectX 6.0 compatibility level or higher)
