Source 2013
The 
Source 2013 engine branch (also called SteamPipe branch) is the final iteration of the Orange Box engine branch. 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. 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 Deathmatch: Source, and 
Half-Life 2: Lost Coast was also upgraded to this engine branch from the Source 2006 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 branch, requires more space due to some Source 2013 games (except 
, 
, etc...) containing duplicated Half-Life 2 base content, plus introducing more bugs to Half-Life: Source. It also does not have most of the 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.
Source 2013 is split into two sub-branches, titled Source 2013 Singleplayer and Source 2013 Multiplayer, which replaced the 
Source 2009 and 
Source Multiplayer branches, respectively. The two sub-branches are mostly interchangeable, but they use separate codebases, and the Multiplayer branch has some features which are not available in the Singleplayer branch.
Tip:Despite the names, both branches can be used for singleplayer.Due to the benefits provided by the Multiplayer branch's additional features (static prop lightmaps, BSP compression, more ambient cubes per visleaf, and slightly newer code), the Singleplayer branch should only be used if using a base mod such as Mapbase, or if making a single-player mod that does not modify game code.
As of 2024, all Source 2013 games are actively being maintained with bug fixes by Valve and third-party developers.
Engine updates since 2022 to the version of 
Source 2013 Multiplayer used by 
Team Fortress 2 have resulted in the creation of a new branch, being the Team Fortress 2 branch, which has its own page.
Contents
Features
Half-Life 2, introduced in 2022.New since the Source 2009 and Source Multiplayer) engine branches are:
- VPK files and
customfolder - 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, users may need to create the custommanually. Source 2013 uses VPK version 2. 
Linux and other 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.
- Static prop lightmaps (only in )(also in
) - Static props without bump maps can now use lightmaps (albeit with limitations).
- Per-texel color tint masking for models
$blendtintbybasealphais ported from the
Left 4 Dead engine branch. Source 2013 includes an exclusive additional parameter, $blendtintcoloroverbase.- BSP compression (only in )(also in )
- BSP maps and packed files can be losslessly compressed on both server and client.
- Raw mouse input
- 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
) - 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 (which, the higher the resolution, the text and UI will become smaller). This UI can be also enabled manually by using -gamepadui command line argument (which will also enable Vulkan renderer that may not work on some older GPUs unless -dx9 is used in combination of -gamepadui).
HL2 20th anniversary update
Bicubic lightmap filtering (only in )- Introduced in 2024, bicubic filtering is used on lightmaps when
r_lightmap_bicubicis enabled, smoothing out aliasing caused by the lower resolution of lightmaps. It can be also enabled by setting the Shader detail to "Very High".
Availability
Gamecode for both the Source 2013 Multiplayer and Singleplayer branches is included in Valve's Source SDK 2013 repository. Full source code (such as Hammer), are not publicly available, but it was leaked back in 2018.
Warning:By default, the SDK 2013 code does not contain many recent updates, new features and bug fixes (such as Dropship gun fix) that was introduced in Half-Life 2 and Portal (since the new 
Steam Deck and 20th Anniversary updates) respectively, nor the "upcoming" builds on Steam, along with the rest of Source 2013 games. Alternatively you can use the SDK 2013 community repos which have these bugs fixed by default. Source 2013 Singleplayer
Valve
2004 Half-Life: Source (formerly 
, 
)2004 Half-Life 2 (formerly , , )2005 Half-Life 2: Lost Coast (formerly )2006 Half-Life 2: Episode One (formerly , )2007 Half-Life 2: Episode Two (formerly , 
)2007 Portal (formerly , )2013
Source SDK Base 2013 - Singleplayer (AppID: 243730 - Click to Install)
Third-Party
2015
Half-Life 2: Update (earlier version)2019
Mapbase2022
Divinia Chronicles: Relics of Gan-Ti- More...
Source 2013 Multiplayer
Valve
2004
Counter-Strike: Source (formerly , , )2005 Half-Life Deathmatch: Source (formerly , )2005
Day of Defeat: Source (formerly , , )2014 Source SDK Base 2013 - Multiplayer (AppID: 243750 - Click to Install)
Third-party
2008
Empires (formerly )2009
Obsidian Conflict (formerly )2008
Zombie Panic! Source (formerly /[confirm])2011
No More Room in Hell (formerly /[confirm])2013
Counter-Strike Online 22014
Fistful of Frags2016
BrainBread 22018
Hunt Down the Freeman (formerly )- More...
Third-party Source 2013 branches
The following games use neither nor , 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 (which also support some features from Alien Swarm, Portal 2 engine branch and onwards, such as partial VTF 7.5 support; formerly , )2015 Black Mesa (has it's own branch known as 
Xengine, had features such as CSM, deferred lighting and more; formerly )
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.
 Windows |
||
|---|---|---|
| Minimum | ||
| Operating system (OS) | XP or later (pre-Steam Deck update) Vista, 7 or later (post-Steam Deck update) |
|
| Processor (CPU) | 1.7 GHz and/or Dual-core | |
| System memory (RAM) | 1 GB (XP) 2 GB (Vista and later) |
|
| Hard disk drive (HDD/SSD) | 3.5 GB | |
| Video card (GPU) | NVIDIA GeForce 6xxx series, ATI Radeon X1600, Intel HD Graphics 3000 (with 128MB VRAM)
Direct3D 9.0 compatible video card (with atleast DirectX 8.0 compatibility level or higher) |
|
| Other | To play on XP and Vista, run the game without Steam by directly launching the hl2.exe executable. Some games may requires -game <gamename> command line. |
|
 macOS (OS X) |
||
|---|---|---|
| Minimum | ||
| Operating system (OS) | OS X 10.5.8, 10.6.3 (up to 10.14.6) | |
| Processor (CPU) | 2.0 GHz and/or Dual-core | |
| System memory (RAM) | 1 GB | |
| Hard disk drive (HDD/SSD) | 3.5 GB | |
| Video card (GPU) | NVIDIA GeForce 8xxx series, ATI Radeon X1600, Intel HD Graphics 3000
OpenGL 2.1 compatible |
|
| Sound (audio device) | OpenAL compatible | |
Note:By default, 32-bit executable are no longer supported after macOS Catalina (10.15), meaning that SDK 2013 will not work out of the box. User can manually build Intel 64-bit/Apple Silicon executable by following this guide.| Linux |
||
|---|---|---|
| Minimum | ||
| Operating system (OS) | Ubuntu 12.04, SteamOS 1.0 or later Other Linux distros supported. |
|
| Processor (CPU) | 2.0 GHz and/or Dual-core | |
| System memory (RAM) | 1 GB | |
| Hard disk drive (HDD/SSD) | 3.5 GB | |
| Video card (GPU) | NVIDIA GeForce 8xxx series, ATI Radeon X1600, Intel HD Graphics 3000
OpenGL 2.1 compatible |
|
Note:The system requirements for Linux are unofficial, based off Windows/Mac info, as well as other Source games that support Linux, such as Portal 2.
