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Source 2006

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Source 2006
Developer(s)
Release date(s)
June 1, 2006
Latest release(s)
December 3, 2009
(last engine & SDK Base update)
Status
Discontinued, SDK tools & SDK Base remains available
Platform(s)
Predecessor
Successor
Orange Box branch Orange Box branch
(2007, 2009/MP)
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This article is about the Source 2006 engine branch. For the documentation on Source SDK Base 2006, see Source SDK Base.
HDR, while technically introduced in Day of Defeat: Source Day of Defeat: Source, was one of the features demonstrated in Half-Life 2: Lost Coast Half-Life 2: Lost Coast, a tech demo.[2][3] These features are shipped by default with the release of Source 2006 Source 2006. This image compares between LDR, LDR with Bloom and HDR.

The Source 2006 Source 2006 engine branch, also known as the Episode One engine branch, and the last Old Engine branch, was first introduced in 2006 with Half-Life 2: Episode One Half-Life 2: Episode One, with all previous games on Source 2004 Source 2004 (except Half-Life 2, Half-Life 2: Lost Coast, and Half-Life: Source) upgraded to this branch. Some features of Source 2006, such as HDR rendering and color correction, are first demonstrated in 2005 with Half-Life 2: Lost Coast Half-Life 2: Lost Coast and Day of Defeat: Source Day of Defeat: Source (both of them runs on a updated version of Source 2004 when initially released).

Source 2006 (circa July 29, 2006‎) also introduces Source SDK Base (the 2006 version of SDK Base was later renamed to Source SDK Base 2006). Mod that are based on SDK Base instead of directly on Half-Life 2 will prevent incompatible engine updates (like Half-Life 2 upgraded to Source 2009 in 2010 on PC) from making the mod unusable.

It was distributed in base source engine 2.gcf. While it was succeeded by the Source 2007 (also known as Orange Box) branch, Source 2006 continued receiving engine updates until December 2009, and in 2010, all first-party Valve games (except Half-Life: Source and Half-Life Deathmatch: Source) were upgraded to Source 2009. This branch requires Half-Life 2 Half-Life 2 content to operate.

The engine versions for this branch are 2733 (EP1) up to 4044 (Protocol 7).[1]

The SDK and SDK Base game for this branch are free to all Steam users.

Features

Added

Previously introduced since Source 2004 Source 2004 (Day of Defeat: Source/Half-Life 2: Lost Coast engine update):

Anti-aliasing - MSAA up to 8x, and CSAA support.
8x MSAA can now be selected on the menu. Nvidia GPUs (from GeForce 8 up to Kepler-series / GeForce 600 & 700 card) can select CSAA anti-aliasing, which is less demanding than MSAA. CSAA is not supported on Maxwell GPUs (GeForce GTX 750, 750 Ti, 900 series) and later.
Color correction
Alter the color balance of an image to achieve a desired effect. For example, in Day of Defeat: Source Day of Defeat: Source, the color has been adjusted to be more desaturated.
Commentary System
Allows DVD-like director's commentary to be embedded inside levels.
Direct3D 9 - Shader Model 3 (DirectX 9.0+ feature level/dxlevel 95)
Unlocks greatly improved shader performance.
Patching levels with lump files - update entity lumps, changing a .BSP file's entities without recompiling the maps.
Film grain post-processing effect
Used in Day of Defeat: Source Day of Defeat: Source.
High Dynamic Range rendering (DX9 SM2)
HDR rendering (also known as HDR lighting) simulates brightness values outside computer monitors' actual range, before downconverting to Wikipedia icon small.png Standard Dynamic Range. This mainly involves "blooming" colors above 100% brightness into neighboring areas and adjusting a virtual camera aperture to compensate for any over-exposure that results. HDR rendering gives gives richer colors, better contrast and finer gradients. Not to be confused with HDR display output.
Originally introduced in Day of Defeat: Source Day of Defeat: Source and Half-Life 2: Lost Coast Half-Life 2: Lost Coast (runs on newer version of Source 2004), but generally attributed to Source 2006.[2][3]

New since Source 2004 Source 2004:

BSP version 20
New BSP version, with new lumps.
Detail prop shapes
Improved detail sprites that sway in the breeze and bend away from nearby players.
Dynamic interactions
Dynamic interactions between NPCs using special animations.
Facial animation upgrades
More detail and intenser shapes for close-up performances.
Improved prop_static lighting
Static props without normal maps or phong can now be lit by VRAD per-vertex, instead of at runtime based upon their origin or $illumposition.
Lightwarp textures (DX9+ SM3)
1D textures that tint a material per-texel depending on their brightness.
Phong materials
Diffuse reflections for skin and other roughened surfaces on models.
Note.pngNote:Some features above are only available with Direct3D 9, dxlevel 95 (DX9.0+ level) or later.

Removed

Steam Friends menu (in Half-Life 2).
DirectX 6.0 (dxlevel 60) compatibility level
Support for DirectX 6.x GPUs has been partially dropped, but is still usable.
Steam Friends menu (and Friends v2)
In-game friends list & instant messaging, allowing you to chat in-game without Alt + Tab to Desktop and open Friends in Steam client. Source 2006 uses Friends v2 (formerly Friends Beta), which removes Parlor Games option (a feature which allows player to play Checkers, Chess, Go, Hearts and Spades with friends), and relies on Steam API instead of Steam TrackerNote servers which has been shutdown.
Originally present before it was eventually removed in August 2007 engine update for Source 2006 (build date July 31, 2007), as many of it's functionality are replaced by Steam Overlay which is introduced with the launch of Steam Community, and the Steam update on the same day (August 6, 2007).[4] As of 2025, the friends feature (still works with latest Steam client) only works on Source 2004 games since 2006 (when Friends Beta was introduced), and all Source 2006 games before the "Friends" feature being removed. It can send messages to friends (the message is shown on Steam client, but not in-game). The Friends feature on older build of Source 2004 and GoldSrc (both from 2005 or earlier) no longer works, since the old Tracker server was offline.

Availability

Game code for the 2006 branch is included in the now-deprecated Source SDK app. To compile the code for 2006 branch, see Compiling under VS2005.

All Valve games introduced with Source 2006 and previous titles that are upgraded from Source 2004 Source 2004 to Source 2006 Source 2006 are now currently using Source 2013 Singleplayer or the Team Fortress 2 branch (previously Source 2013 Multiplayer).

Usage

The following games still run on Source 2006 Source 2006:

Valve

Third-Party

Standalone

SDK Base Mod

History and changes

May 2, 2006: The successor to Source 2004, a very first build of Half-Life 2: Episode One running on Source 2006 was built on this day, along with May 6, 2006 and May 30, 2006 build (the latter became the build that Episode One was shipped with), but Half-Life 2: Episode One wasn't released until June 1, 2006. The May 2 build can be only found in Half-Life 2: Holiday 2006 physical copy.
June 1, 2006: Half-Life 2: Episode One was released, which ran on Source 2006 engine and succeeded Source 2004. Counter-Strike: Source, Half-Life 2: Deathmatch and Half-Life Deathmatch: Source was also upgraded to this engine from Source 2004. Half-Life 2 and other Source titles continued to run on Source 2004.
August 6, 2007: Around this time, Source 2006 titles received updates that removes the "Friends" menu option and the "Friends" in-game messaging feature. This update was released on the same day when the Steam Community was launched, and the Steam client update on that same day, adding in-game overlay (Steam Overlay), which replaced in-game "Friends" menu feature. Unlike Source 2004, which removes the Friends features by mounting half-life 2 game dialog.gcf file, Valve directly updated the base source engine 2.gcf file and also modified the Source 2006 engine to completely remove the "Friends" feature, this means that even if the user managed to replace the content of "PlatformMenu.vdf" file (inside base source engine 2.gcf/platform/steam/games) with one before the Friends feature was removed (like one taken from Source 2004's source engine.gcf), and restores the "Friends" menu option by replacing GameMenu.res, trying to open "Friends" via the menu or the gamemenucommand OpenFriendsDialog will have no effect.
July 2, 2008Day of Defeat: Source - Palermo Update was released. This update upgraded the game from Source 2006 to Source 2007, adds 51 achievements (now 54) to the game, "nemesis/revenge" freeze cam like Team Fortress 2, and adds one new map, dod_palermo.[5]
January 21, 2010: Vindictus (also known as Mabinogi Heroes in Asia), a MMORPG game was released. The third-party game uniquely runs on heavily modified Source 2006 branch, despite the availability of Source 2007 and later branches by the time the game was released. This is likely because the game development started around the time Source 2006 was released.
New feature includes: Engine limits was increased and the game uses proprietary .hfs compressed file format to store game assets. Later in late 2010s and 2020s, many features that can be found in newer Source engine branches and other modern game engines (like Unreal Engine) were added to the game, such as Texture streaming, Nvidia PhysX, 64-bit binaries, XInput (Xbox) controller support and Direct3D 11 renderer.
May 26, 2010Half-Life 2: Episode One was upgraded from Source 2006 to Source 2009 (Orange Box) engine when Valve releases Steam for macOS and ported Half-Life 2 (and it's episodes) to macOS. The new engine update was initially exclusive to macOS, but later released for Windows in June 10, 2010.[6] Counter-Strike: Source and Half-Life 2: Deathmatch was the only Valve games that still runs on Source 2006.
June 23, 2010Counter-Strike: Source was upgraded from Source 2006 to Source 2009 when a major update and overhaul was released, adding various new features, 144 (now 147) achievements and similar to DOD:S new update, "nemesis/revenge" freeze cam like Team Fortress 2.[7] The new update was co-developed with Hidden Path Entertainment (who later co-developed CS:GO). Half-Life 2: Deathmatch and Half-Life Deathmatch: Source became the only Valve games that still runs on Source 2006.
September 30, 2010Half-Life 2: Deathmatch was upgraded from Source 2006 to Source 2009.[8] This leave Half-Life Deathmatch: Source as the only Valve game that still runs on Source 2006.
September 27, 2013Half-Life Deathmatch: Source, being the last Valve title that still runs on Source 2006 and being hosted on Steam, was upgraded from Source 2006 to Source 2013 Multiplayer on Windows during SteamPipe transition.[9] Half-Life: Deathmatch Source was previously ported to macOS (OS X) and Linux (both runs on Source 2013 MP) during a beta test in September 13, 2013.[10] Third-party games (includes SDK Base 2006 mods) are now the only games, that still runs on Source 2006 along with Source SDK Base 2006 itself.

Known issues

Icon-Bug.pngBug:All Source 2004 and 2006 games suffered from the fog bug that makes it more dense than usual, which was affected on newer GPUs (since GeForce 8000 series or newer AMD/ATI GPUs) and newer drivers. This has been fixed on NVIDIA systems since driver version "516.5x" (confirmed on RTX 3060),[11][12] but is likely still present on AMD/Intel. This issue is not affected when using dxlevel 81 or lower, only dxlevel 90 or higher.

Additionally, using any D3D9 wrapper (which translates to D3D11, D3D12 or Vulkan), like Pcgw icon.png dgVoodoo 2 (even on systems with newer NVIDIA drivers that fixes this issue) on this branch, can also cause this issue.

Source - Old Engine fog bug.jpg

Note.pngNote:This driver fix also makes VGUI UI (on DirectX 9 mode) looks dark exactly like DirectX 8 or lower. However, VGUI (in DirectX 9) will still look bright on Source 2007 and later.
  (tested in: SiN Episodes, Counter-Strike: Source v34, Half-Life 2)
Icon-Bug.pngBug:Switching resolutions in some of Source 2006 games, may cause the right side of the HUD (ammo) to be improperly scaled. Some console text such as one that displayed by enabling cl_showfps or cl_showpos 1, will be either cut off or completely hidden.  (tested in: GMOD 9, HL2 old engine)
Icon-Important.pngImportant:All Source games prior to Left 4 Dead engine branch or Source 2013 are known to have slower Alt + Tab and can occasionally crash easily, especially when running on modern version of Windows.

System Requirements

Minimum Specs :

Note.pngNote:As Steam dropped support for previous version of Windows, and this branch requires Steam (unlike Source 2013), all Source 2006 branch games will require Windows 10 or later. Source 2006 games are still currently playable with the last version of Steam running on Windows 7/8/8.1.

References

1. Source Engine Build List - Google Spreadsheets

Updated Source Engine Build List - VDC (with post-2021 engine updates and corrections). Retrieved on February 25, 2026. 

2. See PDF. Lost Coast did not use base source engine 2.gcf (Source 2006 binaries), and so with Day of Defeat: Source, the latter only used it after engine update in 2006. Also SiN Episodes SiN Episodes, a Source 2004 game which was built on DODS / Lost Coast version of Source 2004 engine, have non-functional HDR console command mat_hdr_level, but also does not support BSP 20 from DODS/Lost Coast.
3. Confirmed by downloading older versions of Day of Defeat: Source through Internet Archive (Steam2 Chunks archive from 2005-2009).

The release version of DOD:S (runs on Source engine build 2497, dated Sep 8 2005), support HDR out of the box. It also have Commentary System (which is unused in this game, but later used in Half-Life 2: Lost Coast). Additionally the Source 2004 binaries (depot 200), aka source engine.gcf, used in Day of Defeat: Source and Half-Life 2: Lost Coast, also had dxlevel 95 mentioned on dxsupport.cfg. --leonidakarlach (talk) 09:21, 17 April 2025 (PDT).

4. The Steam in-game overlay was silently introduced with the release of The Steam Community Update in August 6, 2007 as a public beta, alongside the launch of Steam Community on the same day. This update was later rolled out to all users on September 13, 2007. The in-game overlay wasn't mentioned on the changelog until Steam client September 18, 2007 update. Retrieved on May 13, 2025. 
5. Valve Corporation (July 2, 2008), Day of Defeat: Source - The Palermo Update (Archived). Steam. Archived from the original on December 16, 2008. Retrieved on February 25, 2026. 
6. Valve Corporation (May 26, 2010), Half-Life 2, Half-Life 2: Episode One and Half-Life 2: Episode Two Updates Released. SteamArchived from the original on May 28, 2010. Retrieved on February 25, 2026. 

Half-Life 2, Half-Life 2: Episode One, Half-Life 2: Episode Two
:- Added support for Mac

7. Valve Corporation (June 23, 2010), Counter-Strike: Source Update Released. SteamArchived from the original on June 27, 2010. Retrieved on February 25, 2026. 

Updates to Counter-Strike: Source have been released and the game is now available on the Mac. To celebrate this update, Counter-Strike: Source will be on sale for 66% off until Friday.

8. Valve Corporation (September 30, 2010), Team Fortress 2 Update Released. SteamArchived from the original on October 2, 2010. Retrieved on February 25, 2026. 

Other Games

- Half-Life 2: Deathmatch
- Updated to run on the Orange Box engine with CS:S, DoD:S, and TF2

9. Valve Corporation (September 27, 2013), Half-Life Deathmatch: Source update released. SteamArchived from the original on September 2, 2021. Retrieved on February 25, 2026. 

We have updated the public release of Half-Life Deathmatch: Source. This update contains all the changes from the recent beta, thanks to the whole community for their help with testing and suggesting new features.

Changes in this update are:

- Converted Half-Life Deathmatch: Source to the new SteamPipe content system, for optimized delivery of the game
- Added support for Linux and Mac OS X operating systems
- Numerous bug fixes contributed by community members

10. Valve Corporation (September 12, 2013), Half-Life Deathmatch: Source update released. SteamArchived from the original on February 25, 2026. Retrieved on February 25, 2026. 

In support of the Steam for Linux release we have made Half-Life Deathmatch: Source available on Linux and Mac OS X.

This beta involves significant changes for all platforms and your testing is appreciated, please report any bugs to our GitHub page.

Linux and OS X users can simply install the Half-Life Deathmatch: Source application to access the beta.

For Windows users right click the game in your Library, choose properties and then go to the Beta tab. Select the SteamPipe beta to start testing. Under windows to opt out of testing simply deselect the beta option on this same page.

11. Source DirectX9 grey fog bug
a0divided: This bug basically only happens while using DX9 with games that run on pre-Orangebox versions of Source, like Sin as mentioned above or HL2 & EP1 before the 2010 engine update.

But what's interesting is that this bug was fixed at some point by Nvidia, at least on their newer cards with the latest drivers. I currently have an RTX 3060 Laptop GPU with driver 516.5 and the fog actually works properly on DX9. Unfortunately, I think it's still bugged with AMD or Intel GPUs.... Retrieved on June 12, 2025. 

12. Verified by leonidakarlach (talk) 01:36, 14 September 2024 (PDT):
Appeared to be fixed. Using RTX 3060 (desktop) and driver version 560.81. Using something like DgVoodoo2 would break this again..

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