Source 2013

The engine branch (also called SteamPipe branch) is the final iteration of the . It was introduced by Valve in 2013 to replace the archaic GCF file format with the VPK format introduced in the . Major shifts in content mounting occurred, and all Valve games using the and engine branches were upgraded to this branch. , , and was also upgraded to this engine branch from the engine branch. The 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 code, it also broke countless numbers of mods and worsened problems already present in the branch, requires more space due to some Source 2013 games (except , , etc...) containing duplicated base content, plus introducing more bugs to . It also does not have most of the features that the engine branches from the 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 , NPCs eyes not blinking, etc...) and is now the main branch in use by modern non-licensed engine mods.
 is split into two sub-branches, titled and , which replaced the and 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.
As of 2024, all games are actively being maintained with bug fixes by Valve and third-party developers.
Engine updates since 2022 to the version of used by have resulted in the creation of a new branch, being the , which has its own page.
== Features ==
New since the and engine branches are:
; VPK files and folder
: First introduced on and onwards, it was later available on , 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 , users may need to create the manually. Source 2013 uses VPK version 2.
; , , other OS and cross-platform support
: The engine can now run on Linux, Android (for Shield), and other operating systems/platforms. However, support for these OS outside of official games may be spotty.
; Static prop lightmaps 
: Static props without bump maps can now use lightmaps (albeit with limitations).
; Per-texel color tint masking for models
: $blendtintbybasealpha is ported from the . includes an exclusive additional parameter, $blendtintcoloroverbase.
; BSP compression 
: BSP maps and packed files can be losslessly compressed on both server and client.
; Direct3D 9Ex / Windows Aero DirectX Extensions 
: Improve performance depending on GPU hardware and drivers.
: 
; 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 
: Introduced in 2022, Gamepad UI is a modern controller-oriented UI designed for consoles and handhelds like . 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 command line argument, or running the game when Steam Big Picture mode is active.Enabling Gamepad UI will also enable Vulkan renderer. If your GPU doesn't support Vulkan or if you don't want to enable Vulkan, uses alongside the command.
; Vulkan renderer 	
: A low-overhead, cross-platform graphics API, successor to OpenGL.	
: First introduced in 2022 with and . 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 into the game's launch options.
=====HL2 20th anniversary update===== 
; VGUI High DPI support 
: VGUI are now properly scalable on higher resolutions such as 4K (3840x2160).
; lightmap filtering 
: Introduced in 2024, bicubic filtering is used on lightmaps when 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 
: 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 "Use Radial Fog " KeyValues.
; 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 console command.
== Removed features ==
; Patching levels with lump files 
: Patching levels using lump files (to change the map entities without recompiling the map) is no longer possible in MP branch, and possibly .
; Built-in VR headset support (SteamVR, Oculus VR, etc...) 
: The option to enable VR headset support in Video Options, originally introduced with the release of Source 2013, was removed in later updates of (since 2022 Steam Deck update). Instead, player can install mods such as Half-Life 2 VR Mod to play in VR.
== 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.
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=== 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.
* (which also support some features from , and onwards, such as partial VTF 7.5 support; formerly , ) 
* (has it's own branch known as , 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.
== See also ==
* Source SDK 2013
* Source SDK 2013 community repos
Category:Official Engine Branches