| Release date |
Title |
Developer |
Platforms |
Features |
Source code |
Notes    
|
| 7 Oct 2004 |
 Source 2004 |
Valve Corporation |
PC: Windows |
Initial release:
• Direct3D 9 (FL 6.x to 9.0), up to Shader Model 2.0
• Up to 6x MSAA (modern systems only support up to 4x)
• Xbox support
Updated version ( / ):
• HDR Rendering
• Film grain post-processing effect
• Color correction
• Direct3D 9 (FL 6.x to 9.0+) up to Shader Model 3.
• Up to 8x MSAA and CSAA support.
• VTF 7.2 support
• More on Source 2004 - Features page.
|
 GitHub (unofficial archive)
(includes SDK code & tools) |
First released with Counter-Strike: Source, later used by Half-Life 2, Half-Life: Source. Later received HDR update in 2005 with the release of Half-Life 2: Lost Coast. |
| 1 Jun 2006 |
 Source 2006 |
Valve Corporation |
PC: Windows |
• See Source 2006 - Features page.
|
Source SDK Base 2006
 Source SDK application
(includes SDK code & tools)
GitHub (unofficial archive)
(SDK code only) |
Released alongside Half-Life 2: Episode One, all previous Valve games using Source 2004 were upgraded to this branch. See Features section for the list of changes and new features. |
| 10 Oct 2007 |
 Source 2007 |
Valve Corporation |
PC: Windows
Consoles: Xbox 360, PlayStation 3 |
• Achievements support
• Xbox 360, PlayStation 3 support
• Native Xbox 360 controller support
* Threading & Multi-core support
• Particle System
• Bink video
• VTF 7.3 and 7.4 support
• More on Source 2007 - Features page.
|
Source SDK Base 2007
Source SDK application
(includes SDK code & tools)
GitHub (unofficial archive)
(SDK code only) |
Also known as "The Orange Box engine branch". Released alongside The Orange Box (Half-Life 2: Episode Two, Team Fortress 2 and Portal). Half-Life 2 and Half-Life 2: Episode One were also ported to this engine branch exclusively on consoles (Xbox 360, PlayStation 3). See Features section for the list of changes and new features. |
| 17 Nov 2008 |
 Left 4 Dead engine branch |
Valve Corporation |
PC: Windows, macOS (2010)
Consoles: Xbox 360 |
• New menu UI
• Improved threading (multi-core) support
• AI director
• Radial fog and fog volumes
• Support for VPK archive and addons
• Split-screen
• Subtitles for intro & cutscenes
• Shader and effect detail options
• VPhysics optimization for multiplayer
• More on L4D branch - Features page.
|
Left 4 Dead Authoring Tools
 Left 4 Dead 2 Authoring Tools
(no SDK Base, content-based mod only)
Source code: Not publicly available. |
Released in 2008 with the release of Left 4 Dead, and later updated for Left 4 Dead 2 in 2009. Runs on newer version of Source, which does not requires Half-Life 2 base content to run. Game files from this branch were stored into VPK files, as opposed to GCF. See Features section for the list of changes and new features. |
| 3 Jun 2009 |
 Source 2009 |
Valve Corporation |
PC: Windows, macOS (2010) |
• See Source 2009 - Features page.
|
Source SDK application
(no SDK Base, content-based mod only)
Source code: Not publicly available. |
Released in 2009 with an update to Day of Defeat: Source, and later Team Fortress 2. All Source 2006 games (except Half-Life: Source and Half-Life Deathmatch: Source), and Source 2007 were upgraded to this branch with the release of the Mac update in May 26, 2010 (Half-Life 2 and its episodes), and later on Windows in June 10, 2010, alongside Counter-Strike: Source update which features many new changes from Hidden Path Entertainment. |
| 19 Jul 2010 |
 Alien Swarm engine branch |
Valve Corporation |
PC: Windows |
• TileGen
• VTF 7.5 support
• PCF version Binary 5 PCF 2
• Depth of field
• Vertex animation
• More on AS branch - Features page.
|
Alien Swarm - SDK
(includes SDK code & tools)
GitHub (unofficial archive)
(SDK code only) |
Released in 2010 with the release of Alien Swarm, a remake of the Unreal Tournament 2004 mod with the same name. This is the only post-Orange Box engine branch with it's source code publicly available for free. |
| 18 Apr 2011 |
 Portal 2 engine branch |
Valve Corporation |
PC: Windows, macOS, Linux (2014)
Consoles: Xbox 360, PlayStation 3, Nintendo Switch (2022) |
• Improved shadow mapping
• Video playback on materials
• Blob particles
• World portals
• Official PlayStation 3 support
• Steam integration (Steamworks) on PS3
• More on Portal 2 branch - Features page.
|
Not publicly available. |
Released in 2011 with the release of Portal 2. |
| 19 Oct 2011 |
 Source Multiplayer |
Valve Corporation |
PC: Windows, macOS, Linux (2013) |
Same as Source 2009, aside from:
• Direct3D 9Ex (Windows Aero DirectX Extensions) (since Feb 2011)
• Support for Linux operating systems (since Feb 2013)
|
Source SDK application
(no SDK Base, content-based mod only)
Source code: Not publicly available. |
Released in October 19, 2011, when Counter-Strike: Source and other multiplayer titles (Day of Defeat: Source, Team Fortress 2, etc...), which runs on Source 2009, gets updated to this branch. The Source SDK tool & launcher also got updated, which changes multiplayer titles to use Source MP configuration by default. Since atleast May 2011, all multiplayer games uses Protocol version 16 (Source 2009 games use Protocol v15), which would meant that these games use Source MP as far back as May 2011, but Source MP wasn't mentioned until SDK update alongside CS:S update (back in September 2011, changing CS:S's Protocol version to 18).
Linux support was added in February 2013, before Source 2013 Multiplayer was released, and before SteamPipe transition begins in March 2013. |
| 21 Aug 2012 |
 CS:GO engine branch |
Valve Corporation |
PC: Windows, macOS, Linux (2014)
Consoles: Xbox 360, PlayStation 3 |
• FXAA anti-aliasing
• Real-time dynamic shadows (CSM)
• Lightmapped Ambient Occlusion
• Phong reflections on Lightmapped materials
• Texture streaming
• Direct3D 9Ex (Windows Aero DirectX Extensions)
• Scaleform menu UI (2012-2018)
• Panorama menu UI (since 2018)
• More on CS:GO branch - Features page.
|
Not publicly available, but leaked. |
Released in 2012 with the release of Counter-Strike: Global Offensive, featuring many changes not available with previous branches. This engine branch was later made obsolete with the release of Counter-Strike 2, which is the port of CS:GO to the Source 2 engine, which also adds new gameplay features and remakes several maps.
The full source code for this branch alongside Team Fortress 2 (Source 2013) was leaked in 2018. |
7 Feb 2013 (SP)
15 Mar 2013 (MP) |
 Source 2013 Singleplayer
 Source 2013 Multiplayer |
Valve Corporation |
PC: Windows, macOS, Linux
Mobile: Android (Nvidia Shield)
Consoles: Nintendo Switch |
• BSP compression (in all games since ) (not in )
• Support for VPK archive and  custom folder
• Linux, Android and cross-platform support
• Raw mouse input
• More on Source 2013 - Features page.
Updated version (2025 /  Anniversary Update):
•  Bicubic lightmap filtering
• Radial fog
• VGUI High DPI support |
Tools available on bin folder.
(may not be included in some games)
GitHub (SDK Code - Singleplayer)
GitHub (SDK Code - Multiplayer, legacy) |
Released in 2013, during the transition to the new content distribution system called SteamPipe (which has its downsides of breaking many Source mods running on previous branches). All remaining Source 2006 games (Half-Life: Source and Half-Life Deathmatch: Source) and all Source 2009 (including Source Multiplayer sub-branch) were upgraded to this branch. Source SDK Launcher was deprecated on this branch in favor of launching tools (Hammer, Model Viewer, etc.) through .bat files, located in game name\bin. Aside from that, new features has been added along with other improvements. Half-Life: Source and Half-Life Deathmatch: Source, which was upgraded from Source 2006 to Source 2013, now suffering from multiple game-breaking bugs and graphical glitches on some chapters, requiring users to install a unoffical patch in order for it to function correctly.
Full source code for this branch (alongside CS:GO) was leaked in 2018.
Source SDK 2013 Multiplayer has been succeeded by Team Fortress 2 branch in Feburary 18, 2025, while the Singleplayer version received updates first introduced with Half-Life 2 20th Anniversary Update (also added to Half-Life: Source the same day due to being based on Half-Life 2), and later added to Portal in May 2025. Only Source SDK Base 2013 - Singleplayer still runs on older version of Source 2013 Singleplayer without any features from 20th Anniversary Update. |
| 9 Jul 2013 |
 Dota 2 engine branch |
Valve Corporation |
PC: Windows, macOS, Linux |
• See Dota 2 branch - Features page. |
Not publicly available. |
Released in 2013 with the release of Dota 2, and the last official Source engine branch. This engine branch was later made obsolete with the release of the Dota 2 Reborn update, completely upgraded to the new Source 2 engine. |
| 18 Feb 2025 |
 Team Fortress 2 branch |
Valve Corporation |
PC: Windows, Linux |
• 64-bit binaries
• Bicubic lightmap filtering
• Steam Networking
• Texture streaming
• Radial fog
• VGUI High DPI support
• WebM video (x64 only)
• More on TF2 branch - Features page. |
GitHub (Game code only) |
Also referred as Source SDK 2013 Multiplayer v2. It is a updated version of Source 2013 Multiplayer, developed from updates to Team Fortress 2, which have incompatible ABIs, i.e. mods/tools compiled for will not work under  without updating interfaces. It adds features such as VScript, WebM (replaces Bink on x64), 64-bit support, and more...; Aside from Team Fortress 2, Half-Life 2: Deathmatch runs on this branch after the 20th Anniversary update, then in February 18, 2025, all remaining Source 2013 Multiplayer games, as well as SDK Base 2013 - MP, have been upgraded to this branch. |
| Release date |
Title |
Developer |
Platforms |
Features |
Source code & SDK |
Notes
|
Available doc translations 
