Team Fortress 2 engine branch

Team Fortress 2 engine branch

In-game screenshot of Team Fortress 2, running on the Team Fortress 2 branch. This branch adds 64-bit support, VScript support, graphical improvements including bicubic lightmaps (seen here) and radial fog (originally introduced in the Left 4 Dead engine branch), and much more features.

Developer(s)

Valve Corporation

Release date(s)

circa September 16, 2021 - April 18, 2024 (Team Fortress 2)^[1]
February 18, 2025 (public SDK & replaces 2013 MP)

Platform(s)

Windows
Linux

SDK

Source SDK (bin folder)
SDK Base 2013 - MP (2025)

Predecessor

Source 2013 Multiplayer

This article or section needs to be updated to include current information regarding the subject because:

All first party games run on this branch now. Update all other pages to mention the Team Fortress 2 branch instead of Source 2013 Multiplayer, and add new features to this page (if there are any). If something says (only in ), say (in all games since ) instead.

Remember to check for any notes left by the tagger at this article's talk page.

This article is about the engine branch. For documentation of Team Fortress 2 tools, see Team Fortress 2 - Development Documents.

The Team Fortress 2 branch (sometimes referred to as Source 2013 Multiplayer v2, Source 2025 Multiplayer, or the TF2 branch for short) is a newer version of Source 2013 Multiplayer, developed from updates to Team Fortress 2 (since late 2021). Half-Life 2: Deathmatch was also upgraded to this branch after the 20th Anniversary update. All remaining Source 2013 Multiplayer games (, , and SDK Base 2013 - MP) were upgraded to this branch on 18 February 2025, and SDK for this branch was released on the same day.

Currently, this branch, along with Source 2013 Singleplayer, is the latest Source engine branch available, and actively being maintained. It is also the latest branch that are derived from Orange Box, while Portal 2 engine branch became the latest post-Orange Box branch that are still being maintained by Valve, after the release of Counter-Strike 2 and end of support for CS:GO (which includes CS:GO engine branch).

The branch also adds new features, including ones from Half-Life 2's 20th Anniversary Update (bicubic lightmaps), the Left 4 Dead engine branch (radial fog) and other features from later branches.

Some Source mods and tools that are built on Source 2013 Multiplayer (sometimes known as Source 2013 Multiplayer Legacy) will not work on this branch, due to semi-incompatible  ABIs. Nonetheless, the TF2 branch is still considered a sub-branch of Source 2013, alongside Source 2013 Singleplayer and the supplanted Source 2013 Multiplayer.

Features

Added

New since the Source 2013 Multiplayer branch is:

 64-bit binaries (also in for Mac/Linux, )

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.

Bug:The 64-bit versions of some tools, such as StudioMDL, are broken.

VScript (also in )

A powerful new scripting system primarily using Squirrel. First introduced in April 2024 with Team Fortress 2 update. Third-party games may have different VScript implementation.

WebM video playback (64-bit only) (also in )

Used for game intros or cutscenes. WebM allows smaller file sizes without significant degradation in video quality. In the Team Fortress 2 engine branch, it is only used in 64-bit mode, as 32-bit still use Bink & plays Bink video.

Note:Not used in games like Half-Life 2: Deathmatch, Counter-Strike: Source, Day of Defeat: Source and Half-Life Deathmatch: Source, which continues to use Bink, but only when launched with 32-bit executable. 64-bit versions of the game fails to play Valve intro because it uses WebM, and valve.webm isn't present in hl2\media folder.

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. As all Valve games running on Source 2013 Multiplayer branch upgraded to TF2 branch, those games (such as Counter-Strike: Source) now support Vulkan. This is disabled by default (on Windows), but can be enabled in supported games by passing -vulkan into the game's launch options. Vulkan is enabled by default on Linux.

Comparison between VGUI UI scale "1" and "2". Screenshot from Counter-Strike: Source on Team Fortress 2 branch.
(Click to view if GIF does not play automatically).

VGUI High  DPI support (also in 20th, , )

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

Steam Networking (also in )

Allows self-hosting using Steam Datagram Relay, meaning users can easily create joinable servers without port forwarding.

Important:Enabled by default. If you are currently working on mapping for games that have Steam Networking enabled, make sure sv_use_steam_networking is set to 0 (disabled), to prevent users from easily joining your server. Alternatively, uncheck "Use Steam Networking" (in ) or set Server Type to "LAN" or "Friends Only" ( only).

 Bicubic lightmap filtering (also in 20th, , )

Introduced in Half-Life 2 20th Anniversary Update (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".

Comparison between planar-based fog and radial fog. Screenshot from Counter-Strike: Source on Team Fortress 2 branch.
(Click to view if GIF does not play automatically).

Radial fog (also in 20th, , , , all games since )

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. It is first introduced in Left 4 Dead engine branch.

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.

Swaying trees (also in , , , all games since )

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

Updated shader compilation tools

Now by default SCell555's shader compiler is included in the SDK.

Changed / Fixes

VPhysics optimization

All games on Team Fortress 2 now ships with more optimized VPhysics (featured in Left 4 Dead engine branch to CS:GO engine branch), which was meant to improve performance on console and lower end hardware aswell to reduce network prediction errors and servers CPU usage for multiplayer. However this leads to unreliable collision detection due to reduced physics precision.^[2] This means in some cases props and other physics objects will briefly glitch through map object, other props or other physics objects.^[2]

Removed options to disable/enable Direct3D 9Ex (Windows Aero DirectX extensions) in Advanced Video Options.

While the option has been removed, likely because it does nothing when trying to disable it through in-game options/settings (possibly broken since Windows 10), disabling D3D9Ex through -nod3d9ex still works.

Numerous security fixes

See GitHub post.

Fixed building cubemaps

Building cubemaps on this branch no longer requires deleting pre-built (blank) cubemap, and building cubemaps doesn't need cheats to be enabled. However, you still needs to follow some of the steps correctly to make sure you built cubemaps on both LDR & HDR rendering and having consistent exposure/brightness on HDR cubemaps.

Removed

Miles Sound System middleware

Uses open-source minimp3 for MP3 playback instead. Files related to Miles Sound System will remain on the game's bin folder (contains 32-bit DLLs), but left unused.

macOS (OS X) support

Support for Mac was deprecated with Team Fortress 2 update back in 2024 (and applies to all other Source games), due to Mac previously dropping support for 32-bit applications back in 2019, and Valve does not plan to release native 64-bit Mac port.

Known issues / Report bugs

Warning:Unlike Source 2013 Singleplayer and Source 2013 Multiplayer which can be used for singleplayer, TF2 branch makes some changes which break singleplayer mode, such as dysfunctional save loading[1] and attempting to load any map with maxplayers (singleplayer) and cl_localnetworkbackdoor both set to 1 ( or "hl2" only, does not apply to "sourcetest"), and in 64-bit will also crash the game[2]. Some of these bug are unaffected when the game is launched in 32-bit.

Bug:As all games on Team Fortress 2 branch (along with Left 4 Dead to Counter-Strike: Global Offensive and Garry's Mod - x86_64 beta branch only) ships with more optimized VPhysics, which was meant to improve performance on console and lower end hardware aswell to reduce network prediction errors and servers CPU usage for multiplayer. However, this leads to unreliable collision detection due to reduced physics precision.^[2] This means in some cases props and other physics objects will briefly glitch through map object, other props or other physics objects.^[2]  (tested in: All games on )

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

Availability and usage

Source code (game, tools) for this branch is available on GitHub.

To launch tools for these games, go to bin folder (for 32-bit binaries), or bin\x64 folder (for 64-bit binaries).

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 , *, )
• 2013 Source SDK Base 2013 - Multiplayer (formerly ; Click to Install)

Note:Mods built on Source SDK Base 2013 - Multiplayer prior to the upgrade to the Team Fortress 2 branch may not work properly if the mod is launched with updated SDK Base 2013 MP, so if you want to use legacy version of Source SDK Base 2013 - Multiplayer to play older mods (or use older tools), 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.

Note:* - Before Valve distinguish multiplayer games that use Source 2009 MP binaries as Source Multiplayer branch, those games runs on Source 2009, but use separate binaries which are made specifically for MP games, before SDK Update in 10/19/2011 changed TF2, DOD:S and CS:S to use Source MP configuration on the SDK, and thus creating the Source MP branch. The Source 2009 and MP are mostly similar except MP branches received more frequent updates.

Third-Party

• 2009 NEOTOKYO° (as Neotokyo; Rebuild, currently in alpha, currently )
• 2014 Team Fortress 2 Classic - Steam version, coming soon (currently with Mapbase)
• 2019 Pre-Fortress 2 - Steam version, coming soon (currently )
• 2019 Open Fortress - Steam version, coming soon (currently )
• 2024 Team Fortress 2: Gold Rush

System Requirements (SDK)

These system requirements applies to Source SDK 2013 Multiplayer (2025), and some Team Fortress 2 branch based game only. Some other games may have their own system requirements.

Windows
	Minimum
Operating system (OS)	7 or later
Processor (CPU)	1.7 GHz and/or Dual-core
System memory (RAM)	2 GB
Hard disk drive (HDD/SSD)	10 GB (space would be increased depending how many Source SDK mods is installed)
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)

Linux
	Minimum
Operating system (OS)	Ubuntu (20.04), SteamOS 3.0 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)	10 GB (space would be increased depending how many Source SDK mods is installed)
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, as well as other Source games that support Linux, such as Portal 2.

Note:This branch does not support macOS.

References

References

1. Required Versions (SourceMod) According to SourceMod website, TF2 was updated on Sep 16, 2021, which fixes exploits relating to impersonating other Steam accounts, new launch options (-enablefakeip), and more. This however breaks SourceMod plugin, requiring rewriting the plugin to add support for newer versions of TF2. Most of the new features listed here are introduced in April 18, 2024 update for TF2. The remaining Source 2013 MP games (, , and ), and 2013 MP SDK (except the code) was last updated in July 2021 and never receive any new updates again until Feb 18, 2025. Hammer++ (released in 2022) also has a version made specific for TF2.. 2. (Most MP games) Unstable collision detection in VPhysics in modern game builds. (#7426) - GitHub Issues.