Team Fortress 2 engine branch

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The Team Fortress 2 branch is a newer version of Source 2013 Multiplayer, developed from updates to Team Fortress 2. Half-Life 2: Deathmatch was also upgraded to this branch after the 20th Anniversary update. All remaining Source 2013 Multiplayer games (, , and SDK) were upgraded to this branch on 18 February 2025.

The branches have incompatible  ABIs, i.e. mods/tools compiled for will not work under without updating interfaces. The branch also adds new features, including one from Half-Life 2 20th Anniversary Update, Left 4 Dead engine branch and later branches.

Features

New since the Source 2013 Multiplayer branch is:

Swaying trees (also in )

Introduced in Jungle Inferno update. A material parameter that gives the effect of trees swaying in the wind.

 64-bit binaries (also in )

Allows the game to access more than 4GB RAM and have slightly better performance. Additionally, tools such as Hammer, map compilers (VBSP, VVIS, VRAD), etc... also have 64-bit binaries.

Note: 64-bit is not available on Mac.
Half-Life 2 was the first game to receive 64-bit update back in 2005, when it ran on Source 2004. It was later removed for unknown reasons, but it also had some technical issues at the time.
only has 64-bit binaries for the engine DLLs; all executables and game DLLs are still 32-bit.

VScript (also in )

A powerful new scripting system primarily using Squirrel. Third-party games may have different VScript implementation.

WebM video playback (also in )

Used for game intros or cutscenes in some games. Replaces Bink video. WebM allows smaller file sizes without significant degradation in video quality.

Vulkan renderer (also in )

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, and later added to Team Fortress 2 during the 64-bit update. Portal with 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.

VGUI High  DPI support (also in 20th)

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

 Bicubic lightmap filtering (also in 20th )

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 20th)

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.

Texture streaming (also in )

Reduces system RAM and graphics card VRAM usage by streaming textures as needed instead of loading them all when loading the map.

Removal of Miles Sound System middleware

Uses open-source minimp3 for MP3 playback instead.

Numerous security fixes

See GitHub post.

Availability

Game, tools, and exe code for this branch is part of the Source SDK.

Valve

• 2004 Counter-Strike: Source (formerly , , , )
• 2004 Half-Life 2: Deathmatch (formerly , , , )
• 2005 Half-Life Deathmatch: Source (formerly , , )
• 2005 Day of Defeat: Source (formerly , , , )
• 2007 Team Fortress 2 (formerly , , )
• 2014 Source SDK Base 2013 - Multiplayer (formerly ; Click to Install)