Source 2013

The Source 2013 Source 2013 engine branch (also called SteamPipe branch) is the final iteration of the Orange Box engine branch. Built from Source Multiplayer branch,^[5] it was introduced by Valve in 2013 to replace the archaic GCF file format with the VPK format introduced in the Left 4 Dead engine branch, while also upgrading all titles to newer codebase with new engine features. Major shifts in content mounting occurred, and all Valve games using the Source 2009 and Source Multiplayer engine branches were upgraded to this branch. Half-Life: Source Half-Life: Source , Half-Life Deathmatch: Source Half-Life Deathmatch: Source , and Half-Life 2: Lost Coast Half-Life 2: Lost Coast was also upgraded to this engine branch from the Source 2004 (Half-Life: Source and Half-Life 2: Lost Coast ) and Source 2006 (Half-Life Deathmatch: Source ) engine branch. The 🖿custom folder was added to make modding easier and was added as a mounting path for each individual Source game.

While SteamPipe was praised for simplifying how the Source engine mounts content and including previously-unreleased Team Fortress 2 code, it also broke countless numbers of mods and worsened problems already present in the Source 2009 and Source Multiplayer branch, requires more space due to some Source 2013 games (except Half-Life 2: Episode One , Half-Life 2: Episode Two , Half-Life: Source , etc...) containing duplicated Half-Life 2 base content as a result of SteamPipe dropping support for sharing Half-Life 2 base content between games, plus introducing more bugs to Half-Life: Source and Half-Life Deathmatch: Source.

Initially when Source 2013 was released, it also does not add any new features that the engine branches from the Left 4 Dead engine branch onwards had. However, the engine branch has been polished over time, with various bugs from previous Orange Box branch have been fixed (such as Dropship container gun being non-functional in Half-Life 2, NPCs eyes not blinking, etc...) and is now the main branch in use by modern non-licensed engine mods.

Since the release of Half-Life 2 20th Anniversary Update, some features introduced from Left 4 Dead engine branch and later branches are backported to Source 2013, like radial fog (used in Source 2013 Singleplayer and Team Fortress 2 branch ), VPhysics optimization (Team Fortress 2 branch only), and additional improvements & new features exclusive to Source 2013 like VGUI High DPI scaling support, bicubic lightmaps and more, are now available in all first-party games running on both Source 2013 Singleplayer branch and the Team Fortress 2 branch as of 2025, with the exception of Source SDK Base 2013 - Singleplayer.

Sub-branches

Source 2013 is split into three sub-branches. The first two are titled Source 2013 Singleplayer and Source 2013 Multiplayer, succeeding both Source 2009 Source 2009 and Source Multiplayer Source Multiplayer branches respectively. The two sub-branches are mostly interchangeable, but they use separate codebases, and the Multiplayer branch has additional features which are not available in the Singleplayer branch.

Engine updates since 2015 or 2022 to the version of Source 2013 Multiplayer Source 2013 Multiplayer used by Team Fortress 2 Team Fortress 2 have resulted in the creation of a new semi-incompatible sub-branch, being the Team Fortress 2 branch Team Fortress 2 branch , which has its own page. Half-Life 2: Deathmatch Half-Life 2: Deathmatch was also upgraded to this new branch after the 20th Anniversary update. All remaining first-party Source 2013 MP games (Counter-Strike: Source , Day of Defeat: Source , Half-Life Deathmatch: Source ) and SDK Base 2013 - MP have been also upgraded to this new branch in February 18, 2025, completely succeeding Source 2013 Multiplayer branch (also referred as Source 2013 Multiplayer Legacy).

Source 2013 Singleplayer on the other hand, despite also received new features (introduced with Half-Life 2 Steam Deck and Anniversary Update), mod and tools built on older SDK 2013 SP code are still compatible, however, mods that are built with older SDK 2013 SP code running on top of a game built on newer SDK 2013 SP code will not have all features (Steam Input, Radial fog, Classic Particles, HUD Aspect Ratio, etc.) or function correctly. Currently, Valve has yet to release the updated source code for Source SDK Base 2013 SP, but as of May 20, 2025, all Valve titles (except Source SDK Base 2013 - Singleplayer) on the SP branch now runs on updated version of it with features from Half-Life 2 20th Anniversary Update.

As of 2025, the Source 2013 Singleplayer is currently being maintained by Valve, while Source 2013 Multiplayer branch have been succeeded by Team Fortress 2 branch.

Features

New since the Source 2009 Source 2009 and Source Multiplayer Source Multiplayer engine branches are:

VPK files and 🖿custom folder

First introduced on Left 4 Dead engine branch and onwards, it was later available on Source 2013, which replaced the old GCF format. Source 2013 also adds support for reading any files from "custom" folder, which makes installing mods easier without overwriting original game files. In some Source 2013 games, such as Black Mesa Black Mesa , users may need to create the 🖿custom manually. Source 2013 uses VPK version 2.

Linux Linux , Android Android , other OS and cross-platform support

The engine can now run on Linux, Android (for Nvidia Shield), Nintendo Switch and other operating systems/platforms. However, support for these OS outside of official games may be spotty. While Source Multiplayer, since February 2013 was the first branch to run on Linux, Source 2013 supports Linux (and other operating systems) out of the box.

Static prop lightmaps (in all games since Source 2013 Multiplayer)(also in Garry's Mod )

Static props without bump maps can now use lightmaps (albeit with limitations).

Per-texel color tint masking for models

$blendtintbybasealpha is ported from the Left 4 Dead engine branch Left 4 Dead engine branch . Source 2013 includes an exclusive additional parameter, $blendtintcoloroverbase.

BSP compression (in all games since Source 2013 Multiplayer)(also in Garry's Mod )

BSP maps and packed files can be losslessly compressed on both server and client.

Direct3D 9Ex / Windows Aero DirectX Extensions (also in Source Multiplayer Counter-Strike: Global Offensive )

Improve performance depending on GPU hardware and drivers. Additionally, running those games on Windows 10/11 will automatically enable fullscreen optimization, which will allow quicker Alt + Tab ⇆. First introduced in Source Multiplayer,^[4] later available in Singleplayer titles when Source 2013 Singleplayer was released.

Icon-Bug.pngBug:The option to disable D3D9Ex (Windows Aero DirectX Extensions) in Advanced Video Options menu was non-functional and cannot be disabled even with mat_disable_d3d9ex 0. Applications such as Special K (and RTSS only on Source Multiplayer ) still reports the game using D3D9Ex (but not through FlipEx on Source 2013).
To actually disable D3D9Ex, you will need to use -nod3d9ex. Valve have supposedly fixed the issue but it is still present.^[4] Additionally, the option to disable D3D9Ex via Advanced Video Options was removed in Garry's Mod (since July 2025 update), aswell as all games on Team Fortress 2 branch due to it being non-functional.  (tested in: Half-Life 2 (Source 2013 Singleplayer), Garry's Mod 13 Beta (Source Multiplayer ))

Raw mouse input (also in Source Multiplayer )

Directly taking unchanged data from mouse drivers before it goes through operating system enhancements, meaning that mouse input will be exactly 1 to 1.

Steam Deck update

Gamepad UI (only in Half-Life 2 Portal Entropy : Zero 2 )

Introduced in 2022, Gamepad UI is a modern controller-oriented UI designed for consoles and handhelds like Steam Deck. With the new Gamepad UI, it was more scalable across any resolution (including 4K and higher), unlike the regular VGUI at the time (which, the higher the resolution, the text and UI will become smaller). VGUI (except on consoles Xbox 360 /PlayStation 3 ), are harder to navigate, and sometime cannot be navigate with a controller. This UI can be also enabled manually by using -gamepadui command line argument, or running the game when Steam Big Picture mode is active.
Before Half-Life 2 20th Anniversary Update and Portal May 2025 update, enabling Gamepad UI will also enable Vulkan renderer, but you can use -dx9 alongside the -gamepadui command to force Direct3D 9.

Vulkan renderer (only in Windows Linux )(only in Half-Life 2 Portal )(also in Left 4 Dead 2 Portal 2 engine branch CS:GO engine branch Strata Source Team Fortress 2 branch Xengine )

A low-overhead, cross-platform graphics API, successor to OpenGL.

First introduced in 2022 with the release of Steam Deck update for Half-Life 2 and Portal. Portal with RTX and Half-Life 2 RTX also uses Vulkan as part of the RTX Remix runtime. Using DXVK, a library used to translate Direct3D calls to Vulkan. This is disabled by default, but can be enabled in supported games by passing -vulkan into the game's launch options.

HL2 20th Anniversary Update & 2025 SP engine update

These features are exclusive to all games running on updated version of Source 2013 Singleplayer since Nov 2024 and 2025. This include Half-Life: Source Half-Life: Source , Half-Life 2 Half-Life 2 (including Episodes & Lost Coast) and Portal Portal (since May 20). It is not available on Source SDK Base 2013 - Singleplayer. All features listed below are introduced with Half-Life 2 20th Anniversary Update.

VGUI High DPI support (also in Team Fortress 2 branch )

VGUI are now properly scalable on higher resolutions such as 4K (3840x2160).

Wikipedia icon Bicubic lightmap filtering (also in Team Fortress 2 branch )

Introduced in 2024, bicubic filtering is used on lightmaps when r_lightmap_bicubic is enabled, smoothing out aliasing caused by the lower resolution of lightmaps. It can be also enabled by setting the Shader detail to "Very High".

Radial fog (also in Team Fortress 2 branch , Mapbase , all games since Left 4 Dead engine branch )

Unlike planar-based fog, radial fog does not strengthen or weaken the apparent amount of fog in a particular spot when you rotate the camera.

You can either use radial fog or planar-based fog by changing env_fog_controller "Use Radial Fog (fogRadial)" KeyValues.

Note.pngNote:Half-Life: Source and Portal did not use radial fog by default, and Half-Life 2 only uses it for certain maps, but you can force it on using the r_radialfog_force (set to 1) console command.

Continue music playback after loading levels

Introduced in HL2's November 26, 2024 Update, music will continue to play after the next level is loaded, instead of stopping completely like in previous versions. Can be toggled using save_transition_music console command.

Team Fortress 2 branch

Team Fortress 2 branch has its own page.

Removed features

Patching levels with lump files (only in Source 2013 Multiplayer Team Fortress 2 branch )

Patching levels using lump files (to change the map entities without recompiling the map) is no longer possible in MP branch, and possibly Team Fortress 2 branch ^[confirm].

Built-in VR headset support (SteamVR, Oculus VR, etc...) (only in Half-Life 2 )

The option to enable VR headset support in Video Options, originally introduced with the release of Source 2013, was removed in later updates of Half-Life 2 (since 2022 Steam Deck update). Instead, player can install mods such as Half-Life 2 VR Mod to play in VR.

Known issues / Report bugs

To report bugs or find existing issues on this engine branch, see Source games GitHub and Source SDK 2013 GitHub issues page in order to prevent duplicate or outdated bug reports at the wiki.

Availability

Source code

Source code (game, tools) for Source 2013 Singleplayer, Multiplayer and TF2 branch is available on GitHub:

• Source 2013 Singleplayer: Source SDK 2013 GitHub repo.
  
• Source 2013 Multiplayer (legacy version): Source SDK 2013 GitHub repo.
  • Legacy version of SDK 2013 MP code is provided to create & update tools or mods for third-party games built on older SDK 2013 MP code only.
• TF2 branch (newer Source 2013 MP): Source SDK 2013 GitHub repo.

Full source code (such as Hammer and the rest of Source engine), are not publicly available, but code for TF2 branch was leaked publicly in 2020.

Tools

To launch tools for these games, go to 🖿bin folder, then launch the following .bat files:

• hammer.bat - Hammer
• faceposer.bat - Faceposer
• hlmv.bat - Half-Life Model Viewer
• studiomdl.exe - StudioMDL
• vtex.bat - VTEX

Usage

Source 2013 Singleplayer

Valve

• 2004 Half-Life: Source Half-Life: Source (formerly Source 2004 )
• 2004 Half-Life 2 Half-Life 2 (formerly Source 2009 , Source 2004 )
• 2005 Half-Life 2: Lost Coast Half-Life 2: Lost Coast (formerly Source 2004 )
• 2006 Half-Life 2: Episode One Half-Life 2: Episode One (formerly Source 2009 , Source 2006 )
• 2007 Half-Life 2: Episode Two Half-Life 2: Episode Two (formerly Source 2009 , Source 2007 )
• 2007 Portal Portal (formerly Source 2009 , Source 2007 )
  • 2022 Portal with RTX Portal with RTX
  • 2022 Portal Companion Collection Portal Companion Collection (Portal on Nintendo Switch)
• 2013 Source SDK Base 2013 - Singleplayer Source SDK Base 2013 - Singleplayer (AppID: 243730 - Click to Install)

Third-Party

• 2010 Nightmare House: The Original Mod Nightmare House: The Original Mod (formerly Source 2007 )
• 2015 Half-Life 2: Update Half-Life 2: Update (earlier version)
• 2022 Divinia Chronicles: Relics of Gan-Ti Divinia Chronicles: Relics of Gan-Ti
• More...

With Mapbase Mapbase

• 2017 Entropy : Zero Entropy : Zero
  • Originally released before Mapbase. It was later based on Mapbase after updates.
• 2018 Map Labs
• 2022 Entropy : Zero 2 Entropy : Zero 2
• TBA Half-Life 2 RTX Half-Life 2 RTX (Demo released on March 18, 2025.)

Source 2013 Multiplayer

All first-party games and Source SDK Base 2013 MP have been upgraded to the Team Fortress 2 branch.

If you want to use legacy version of Source SDK Base 2013 - Multiplayer, to play older mods (or use tools) built prior to Team Fortress 2 branch, follow the instructions:

1. Open Steam, go to Source SDK 2013 Multiplayer, right click Properties

2. A window will open. Go to "Betas", select previous2021 beta branch.

3. Steam will automatically re-download the files. Once it's done, run Source SDK Base 2013 MP as normal, or use it's tools.

Third-party

• 2007 Fortress Forever Fortress Forever (in development, will replace Source 2006 )
• 2007 Synergy Synergy (formerly Source 2004 , Source 2006 , Source 2007 )
• 2007 Zombie Panic! Source Zombie Panic! Source (formerly Source 2007 )
• 2008 Empires Empires (formerly Source 2007 )
• 2009 Obsidian Conflict Obsidian Conflict (in development, will replace Source 2007 )
• 2010 Pirates Vikings & Knights II Pirates Vikings & Knights II
• 2011 No More Room in Hell No More Room in Hell (formerly Source 2009 /Source Multiplayer ^[confirm])
• 2013 Counter-Strike Online 2 Counter-Strike Online 2
  • Modified with features such as CSM and LZMA-compressed VTF(s).
• 2014 Fistful of Frags Fistful of Frags
• 2016 BrainBread 2 BrainBread 2
• 2018 Hunt Down the Freeman Hunt Down the Freeman (formerly Source 2013 Singleplayer)
• More...

With Mapbase Mapbase

• 2014 Team Fortress 2 Classic Team Fortress 2 Classic (added since patch 2.2.0)

Third-party Source 2013 branches

The following games use neither Source 2013 Singleplayer nor Source 2013 Multiplayer, but rather use custom (heavily modified) branches forked earlier versions from both Source 2013 branches, with newer features added on. As such, they may or may not include all features from newer first-party versions of Source 2013, such as LZMA-compressed BSPs or lightmapped MDLs.

• 2006 Garry's Mod Garry's Mod (formerly Source 2006 , Source 2007 , Source 2009 , Source Multiplayer )
  • Garry's Mod currently ran on modified version of Source 2013 which adds support for certain features from Alien Swarm, Portal 2 engine branch and onwards, such as VTF 7.5 support, and was able to load content from Left 4 Dead engine branch-based games and later.
  • Also, with March 2025 update, uses some code from Team Fortress 2 branch Team Fortress 2 branch for fixing some exploits.
• 2010 Pirates Vikings & Knights II Pirates Vikings & Knights II (formerly Source 2006 , Source 2007 )
  • Runs on a modified version of Source 2013 MP, which includes FMOD audio, Maphack, increased brush and edict limits, Beckmann specular highlighting, 64-bit support, as well as removing DirectX 8 and 8.1 support.
• 2015 Black Mesa Black Mesa (has its own branch known as Xengine Xengine , had features such as CSM, deferred lighting and more; formerly Source 2007 )

System Requirements

These system requirements applies to Source SDK 2013 (and some Source 2013 game) only. Some other games may have their own system requirements.

See also

• Source SDK 2013
• Source SDK 2013 community repos

References

• Pages with uncategorized bugs
• Engine branches
• Source engine branches
• First-party engine branches

• Translation
• English
• CONFIRM