View source for Source

{{LanguageBar}}

{{Source topicon}}

{{Hierarchy}}

{{Infobox engine
| title		 = Source
| image		 = SourceLogoWhite.png
| imagewidth	 = 280px
| imagetooltip	 = Logo of the Source engine.
| image2	 = Screenshot-CSS-Source_engine_comparison.jpg
| imagetooltip2  = Screenshot in-game of {{css|1}}, using the Source Engine, running on [[Team Fortress 2 engine branch|latest TF2 branch]].
| developer	 = [[Valve Corporation]]
| releasedates	 = October 7, 2004 <abbr style="color: #8bb9e0;" title="Counter-Strike: Source is the first Source engine game to be released."><sup>Note</sup></abbr>
| codelang	 = [[WP:C++|C++]], [[WP:C_(programming_language)|C]]
| sdk		 = [[SDK Docs|Source SDK Documentation]]
| platform	 = {{Win|1}}, {{Mac|1}}, {{Linux|1}}, {{xbox|1|nt=1}}, {{360|1}}, {{ps3|1}}, {{switch|1}}, {{android|1}}<br><font style="font-size:12px;">'''''Note:''' Valve (first-party) games only.''</font><!-- only first-party games -->
| sysreq	 = 
| website	 = [https://web.archive.org/web/20110724220714/http://source.valvesoftware.com/ Official Website] (archived)
| links		 = {{github|ValveSoftware/Source-1-Games|GitHub Issues}} (bug report for all Source games, except CS:GO)<br>{{github|ValveSoftware/source-sdk-2013|Source SDK 2013 source code}}<br>{{steamicon}} [https://partner.steamgames.com/doc/sdk/uploading/distributing_source_engine Distributing Source games/mods & FAQ]
| license	 = [[WP:Proprietary software|Proprietary]] <br><font style="font-size:12px;">({{tf2branch}}, {{src13}}, {{asbranch}} source code available for non-commercial purposes.)</font>
| previousengine = {{Gldsrc|2}}
| nextengine	 = {{Src2|2}}
}}

[[File:Screenshot-CSGO-Source_engine_comparison.jpg|340px|thumb|right|Screenshot in-game of {{csgo|1}}. CS:GO used the [[Counter-Strike: Global Offensive engine branch|then latest]] engine branch, which added many new features and graphical improvements.]]

[[File:Apex Legends - Screenshot 5.jpg|340px|thumb|right|Promotional screenshot of {{apex|1}}, which runs on a [[Titanfall engine branch|heavily modified]] version of the Source Engine, featuring DirectX (Direct3D) 11, detailed models and better graphics, plus an increased engine limit. It also uses [[deferred shading]], allowing many dynamic lights to be lit with little to no performance loss.]]

<span style="color:white; font-weight: bold;">{{For|about=the game engine|the documentation on Source and its SDK|[[SDK|Source SDK Documentation]]|}}</span>

{{src|4}} is a 3D game engine created by {{Valve|1}} in 2004, and is the successor to {{gldsrc|3.1}}. The {{src|1}} engine is well-known for its advancements in physics, AI, and graphics which made the games realistic for its time, while being scalable on older, less powerful hardware. One game, {{hl2|1}}, earned several awards for it's graphics, which were made possible with Source. {{src|name}} has been used by [[Valve]], [[#Third-Party|third-party companies]], and (much like GoldSrc) countless community [[Modification|mods]] by people around the globe, with at least 100 games developed on Source. The engine also has [[:Category:Source_engine_branches|several branches]], each with new features added and improved graphical capabilities.

Despite the Source engine being 20 years old, and being superseded by the {{source2|3.1}} engine for first-party usage since 2015, it's still being commonly used today by modders and third-party companies due to the lack of some Source 2 documentation, the sparse availability for third-party licensing, and it's regular maintenance with engine and security updates.

{{Clarify|not all {{src|name}} games have {{VAC|1|nt=0}}. See {{Apex Legends|1}}.}}

== Features ==
List of {{src|4.1}} engine features and capabilities. Some new features listed here may not apply to previous or newer Source branches, or third-party games/branches. 

For a list of Source branches (including third-party games) with their specific new features, [[:Category:Engine branches|see this category page]].

=== [[:Category:Programming|Renderer]] ===
* Supports [[Shader]] Model Versions 2.0 to 3.0
** Some third-party games can also support Shader Model 4.0, 5.0 and later by using D3D versions starting from 11 ({{titanfall}}, {{strata}}, etc).
* [[Anti-aliasing]] support (MSAA, FXAA, MLAA, TAA, etc.)
** See the [[Anti-aliasing]] page for more information, plus features & drawbacks with various anti-aliasing methods.
* More anisotropic and texture filtering options
** Anisotropic filtering allows textures on far distances to look sharper and less blurry.
** Compared to GoldSrc (prior to 2013) featuring only Bilinear or Trilinear texture filtering, {{src|name}} features more texture filtering options, ranging from Bilinear, Trilinear, Anisotropic 2x up to 16x.
* Support for both forward, [[deferred lighting|deferred]] and [[Clustered rendering|clustered]] rendering pipelines.
** Deferred rendering is a rendering technique that allows games to render many dynamic lights with little performance impact. Deferred rendering is commonly used in most modern titles.
** {{hl2|1}} up to {{csgo|1}} uses the forward renderer, while {{dota2|1}}, as well as some third-party Source games ({{titanfall}}, {{bms}}, etc.) use the deferred renderer (shading or lighting).
** Other titles such as {{p2ce|1}} also use the [[Clustered rendering]] technique, resulting in similar lighting performance as the deferred renderer (both clustered, forward & deferred), but unlike deferred, clustered works with both forward & deferred rendering pipelines.
* [[Wikipedia:Bump mapping|Bump mapping]] and [[w:Normal mapping|Normal mapping]] on models and the world
* Authoring of [[shader]]s with [[HLSL]]
* Cube and environment mapping
** Cubemapping also supports Anisotropy {{csgo|since}} 
* [[$phong|Phong]] shading for models
** Phong is also supported on world brushes {{csgo|since}}{{mb|also}}
* Dynamic lights, vertex lighting and [[lightmap]]s, including many light types including flickering, pulsing etc.
* [[HDR]] {{since|{{dods}}}} and LDR (SDR) lighting
** HDR is introduced with the release of {{dods|4}} (and {{hl2lc}} a month later), running on updated version of {{src04|1}}. HDR rendering works by automatically adjust exposure and "blooming" colors above 100% brightness into neighboring areas, then collapsing the image into SDR color range, resulting an image appears to have higher color saturation and improved contrast, compared to SDR (LDR) rendering.
** LDR is deprecated since {{l4dbranch|2}}. This does not apply to some games such as the original release of {{dota2|1}}, for example.
** {{confusion|''Not to be confused with "HDR display output"'', which actually renders the image at higher brightness & better contrast than a SDR monitor is capable of. The Source engine, by default, does not support HDR display output, except in {{apex|2}} on consoles.}}
* Water with refraction, real-time world reflections and Fresnel effects
** Water also supports [[Water (shader)#Special behaviour|flow mapping]] {{l4dbranch|since}}
* [[:Category:Particle System|Advanced particle systems]] that can emit [[sprite]]s or [[model]]s
* [[Dynamic RTT shadow angles in Source 2007|Render-to-texture]] shadows allow for a large number of characters per scene {{l4dbranch|since}} {{mb|also|addtext={{xe}}{{dmmm}}}}
* [[Func occluder|Occluder entities]] for visibility blocking
* Indoor/Outdoor environments
** Deformable terrain
** [[3D Skybox|3D skyboxes]] can extend the horizon and add parallax on distant objects
** Dynamically rendered organics (grass, trees, etc.)
**[[$treeSway|Swaying trees]] {{l4dbranch|since}} {{also|{{tf2branch}}{{xe}}{{gmod}}{{mapbase}}}}
* Subdivision surfaces, diffuse & specular bump maps
* Real-time radiosity lighting
* Real-time [[env_cascade_light|Cascaded Shadow Mapping]] from the skybox {{csgo|since}} {{asd|also|addtext={{cso2}}{{lw}}{{xe}}}}
* Effects that include but are not limited to: particles, beams, volumetric smoke, sparks, blood, and environmental effects like fog and rain
** [[Radial fog]], which prevents strengthen or weaken the fog effect when rotating the camera. Replaces planar-based fog. {{l4dbranch|since}} {{also|{{tf2branch}}, {{hl2}} 20th, {{mapbase}}}}
* Scalability
* [[Screen Space Ambient Occlusion (SSAO)|Screen Space Ambient Occlusion]] (SSAO) {{only|{{sfm}} {{dota2|nt=1}}}}
** A technique for efficiently approximating the ambient occlusion effect in real time.
* Widescreen display support
** {{Source|name}} is one of the earliest game engines to support Widescreen monitors natively (16:9 and 16:10 aspect ratio) without stretching the image, while most games from that era are usually designed for 4:3/5:4 displays only.<br> Games such as {{hl2|1}} supported widescreen displays at launch in 2004, with horizontal FOV (field of view), allow you to see more details.
* [[Physically Based Rendering|Physically Based Rendering]] {{strata|only|addtext={{tfbranch}}{{rr}}{{hdtf}}{{p2d}}}}
* [[Parallax mapping|Parallax Occlusion Mapping]]{{xe|only|addtext={{strata}}}}
* Support of various graphical backends (such as Direct3D, OpenGL, Vulkan)
* Direct3D versions
** [[DirectX Versions#DirectX_9|Direct3D 9]]
*** On earlier versions of Source ({{src04|1}} up to {{src13|1}}), it had a Hardware DirectX level system that allowed older GPUs to run on DirectX 8.0, 8.1 (Pixel Shader 1.x) render paths (disabling DX9 graphical features not available on previous cards). Previous versions of Source ({{src04}} and {{src06}}), as well as Source 2013 RTX Remix games, also had support for DirectX 7.0 and 6.0 render paths. This can be changed using the {{code|[[mat_dxlevel]]}} console command, or by using the {{code|-dxlevel}} [[command line argument|launch option]].
*** {{Note|DirectX hardware level system (and support for all GPUs prior to DirectX 9.0 / Shader Model 2) are no longer supported since {{l4dbranch|1}}.<br>Also, regardless which {{code|dxlevel}} was set to, all Source games will always run on Direct3D 9.}}
** [[DirectX Versions#D3D9Ex|Direct3D 9Ex]] {{src13|since}} {{also|{{srcmp}}<abbr style="color: #8bb9e0;" title="Added since 2011."><sup>Note</sup></abbr>, {{csgo}}}} - DX9 Windows Aero extensions, requires {{Win7|3.1|nt=Vista}} or later. Users can enable/disable this in Video Settings - Advanced (Windows Aero extensions), or through the [[command line argument|launch option]] {{code|-disable_d3d9ex}} {{csgo|only}}.
** [[DirectX Versions#DirectX_11|Direct3D 11]] {{tfbranch|only|addtext={{strata}}{{Vindictus}}}} 
** [[DirectX Versions#DirectX_12|Direct3D 12]] {{Apex|only}}
**{{Note|[[DirectX Versions|Direct3D 9]] can be forced by the launch option {{code|-dx9}}, if it was forced by commands such as {{code|-gamepadui}}, which enables both the [[Gamepad UI in mods|Gamepad UI]] and Vulkan renderer unless combined with {{code|-dx9}}}}
* [[OpenGL]]{{src09|since|addtext= /{{srcmp}}}} which is another graphics API used in Source games on {{mac|1}} and {{Linux|1}}.
** Source Engine ships with ToGL to translate Direct3D (DirectX) calls to OpenGL, and uses {{code|dxlevel 92}}, which is the [[OpenGL]] equivalent to DirectX 9 Shader Model 3 (D3D9.0c).
*[[Vulkan]] graphics API {{hl2|only|addtext={{portal}}{{rr}}{{l4d2}}{{portal2}}{{csgo}}}}
** A low-level API, and the successor to OpenGL. Vulkan can be used to workaround various graphical issues such as {{portal2|4}}'s [[Env_projectedtexture|projected textures]], which does not render properly on newer graphics drivers (both NVIDIA and AMD). Vulkan can be enabled by using the {{code|-vulkan}} [[command line argument|launch option]].
{{note|{{csgo|2}} only supports Vulkan on {{Linux|1}}}}
{{note|Source allows up to 8 [[LOD Models]], although it does not have automatic [[w:Level of detail (computer graphics)|level of detail]] out of box. Manual LoD is supported, however.}}
{{warning|{{csgo|2}} currently does not support level of detail. [[$lod]] will be ignored, but the model will still work. Try to avoid using this command in {{csgo}}.}}

=== [[:Category:Material System|Materials System]] ===
* Instead of traditional textures, '''Source''' defines sets of materials that specify what the object is made from and the texture used for that object. A material specifies how an object will fracture when broken, what it will sound like when broken/interacted with, and what that object's mass and buoyancy are. This system is much more flexible than older texture-only systems.
* Materials can interact with objects or [[NPC]]s, such as mud or ice for vehicles to slide/lose traction on.

=== [[Source Multiplayer Networking|Multiplayer Network Code]] ===
* Time- and gamer-tested by millions of people around the world
* Support for both [[wikipedia:Local area network|LAN]]-based multiplayer and Internet-based multiplayer games
* Prediction analysis for interpolating collision/hit detection
* Optimizations for high-latency, high-packet-loss 56k connections
* [https://partner.steamgames.com/doc/features/multiplayer/networking Steam Networking] support {{only|{{tf2branch}}{{synergy}}}}
** Allows self-hosting using [https://partner.steamgames.com/doc/features/multiplayer/steamdatagramrelay Steam Datagram Relay], meaning users can easily create joinable servers without port forwarding.

=== [[:Category:Modeling|Advanced Characters]] ===
* Detailed and believable characters
* Realistic [[Eyeball|eyes]]
** Focus on player/object, not simply parallel views
** Proper eye bulge for realistic eye reflections
* Simulated musculature provides outstanding emotions, speech, and body language
* [[:Category:Choreography|Language independent speech]], characters can speak naturally in many languages
* Skeletal/bone system for animation
* Layered animation system can synthesize complex animations out of several pieces

===[[:Category:Physics|Physics]]===
* Source uses the [[Havok]] physics engine, licensed from the Havok Group (now acquired by [[w:Microsoft|Microsoft]])
* A more responsive world with more realistic interactions
* AI characters can interact with physically simulated objects
* Includes support for ropes/cables, machines, constraint systems, and [[w:Ragdoll physics|ragdoll physics]]
* Can be controlled by level design
* Kinematic animated bone followers
* Custom procedural physics controllers
* Vehicles
** Wheels slip and skid
** Realistic suspensions with springs on each wheel
** Realistic leaning during acceleration/deceleration and turning
** Individually tunable parameters such as horsepower, gearing, max speed, shift speed, tire material, tire friction, spring tension/dampening, etc.
** Multiple players/NPCs in a vehicle
** Hovercraft support for cheaper simulation

=== [[:Category:AI|Advanced AI]] ===
* [[Inputs and Outputs|I/O system]] allows level designers to control AI
* Sophisticated navigation: characters that run, fly, jump, crouch, climb stairs and ladders, and burrow underground
* AI that senses things using sight, sound, and smell
* [[ai_relationship|AI relationships]] determine friend/foe status of other entities
* Battle AI allows squads of AI characters to operate together, knowing when to advance, retreat, lay cover, fire, etc.

=== [[:Category:Sound System|Sound System]] ===
* Uses the [https://www.radgametools.com/miles.htm Miles Sound System] as middleware (except in some third-party games) or the free & open-source [https://github.com/misyltoad/VAudio-MiniMP3 VAudio minimp3] {{since|{{tf2branch}}}}
* Support 7.1, 5.1 surround sound, 4 speaker surround
: {{Bug|Despite all Source games prior to {{as|1}} having the 7.1 audio option, the game only outputs only 5.1 surround despite 7.1 selected. This issue does not affect some third-party games, such as {{titanfall2|1}}, and {{apex|1}} as they used newer versions of the Miles Sound System, which have this problem fixed.}}
: {{Note|Some or newer Source games (such as {{as|1}}, {{portal2|1}} and {{csgo|1}}) may not include options to enable 7.1 surround sound without using console commands.}}
* High-quality 3D spatialization
* Custom software [[DSP]]
* Automatic DSP based on environmental geometry
* Microsoft ADPCM-compressed [[WAV]] files
* 16-bit 44.1 KHz (CD Quality), stereo wave data with all features
: {{Note|Source does ''not'' support 48 KHz audio (DVD Quality) by default.}}
* [[MP3]] decompression
** MP3 decompression used in many Source games requires [http://www.radgametools.com/miles.htm licensing from Epic (RAD) Game Tools]. Alternatively, [https://github.com/misyltoad/VAudio-MiniMP3 minimp3] may be used instead.
* Support for audio streaming on any wave {{clarify}}
* Real-time wave file stitching {{clarify}}
* Pre-authored Doppler effect encoded waves
* Pre-authored distance variant encoded waves
* [[Commentary System|Commentary system]]

=== [[:Category:VGUI|UI]] ===
<div style="float:right">
[[File:Ep2_menu.jpg|340px|thumb|Screenshot of {{hl2ep2|1}} main menu, which is rendered using VGUI, with '''New Game''', '''Options''', and '''Achievements''' window opened.]]
[[File:HL2_GamepadUI_menu.png|340px|thumb|Screenshot of VGUI's Gamepad UI used in some {{src13|1}} games after 2022. This UI was enabled by default when playing on {{deck|1}}.]]
<!-- TODO: CSGO menu -->
</div>

* '''Server browser''' — Displays all active game servers and allows a player to choose which one to participate in. Players can filter and sort server lists to speed up the display and selection of a server.
* '''[[:Category:VGUI|VGUI]]''' — Valve's custom GUI interface mimics OS windows but renders them using the '''Source''' engine for both in game and out of game uniform '''UI''' display.
** Dynamic in-game [[HUD Elements|HUD]] display
** Many [[wikipedia:Graphical widget|widgets]]/controls (e.g., buttons, treeview, html control…)
** Themes/custom visualization allowed
** Platform independent
** Localized text (Unicode compliant)
** '''[[Gamepad UI in mods|Gamepad UI]]''' <!-- TODO: Create a page about Gamepad UI in general --> ({{src13|4.1}} version) — Since the release of {{hl2|3.1}} (and its episodes) as well as {{portal|3.1}} updates in 2022, Valve have added a modern UI which is designed for consoles and handhelds like the {{steamdeck|2}}. With the new Gamepad UI, the UI is scalable across any resolution (including 4K and higher), unlike the regular VGUI, which does not automatically scale up to the resolution. This UI can be enabled manually by using the {{code|-gamepadui}} [[command line argument]] (which will also enable the [[Vulkan]] renderer that may not work on some older GPUs unless {{code|-dx9}} is used in combination of {{code|-gamepadui}}).
* '''Scaleform''' (''officially called '''Scaleform GFx''''') — Introduced with {{csgobranch|1}} at launch, is a vector graphics rendering engine used to create {{flash|4}}-based UIs and HUDs for Source games. Also used in {{dota2|2}}. Both games eventually replaced Scaleform with Panorama (circa 2015{{confirm}} with the {{Dota2|name}} Reborn update, and in 2018 for CS:GO when it went free to play, along with the Danger Zone update).
* '''[[Panorama]]''' {{csgo|since}} — The successor to Scaleform, introduced in 2018, is Valve's new custom GUI interface that ressembles modern web design and authoring (HTML5/CSS/JS). Using <code>[[WP:XML|.XML]]</code> and JavaScript files, developers can create dynamic and clean HUDs and menus and even high-quality in-game interactable panels.
{{clr}}

=== Input ===
Source supports the following input and controller APIs:
* DirectInput - this method is supported in previous Source branches ({{src04}}, {{src06}}).
* XInput - Introduced with {{src07|4}}, this allows the game to be controlled using Xbox 360, Xbox One & Series X/S controllers. On some Source games this was superseded by the Steam Input API, but can be re-enabled by disabling the Steam Input API.
** Since the {{hl2|1}} 20th Anniversary Update and the {{portal|1}} (May 2025 update), the option to enable legacy gamepad support (XInput and DirectInput), has been removed (which also unintentionally breaks the vibration/rumble feature when using the Steam Input API). However you can use the {{code|joystick 1}} console command to re-enable legacy controller support (which also enable rumble/vibration support even when using Steam Input).
* Steam Input API - control the game using almost any controller (Xbox, PlayStation, Nintendo, and others). Many of Valve's Source games have been updated to natively support them.
** For the list of games that natively support Steam Input API, see [[Steam#Steam_Input_API|this page]].

=== [[:Category:Programming|Programming]] ===
* Source natively support various CPU architectures, such as x86 (PC and 8th, 9th-gen Consoles), ARM ({{Android|2}}, {{Switch|2}}), PowerPC ({{360|2}}, {{ps3|2}}), and more, with both 32 and [[w:64-bit|64-bit]].
** Support for [[w:64-bit|64-bit]] architecture will allow Source to handle more than 2-4GBs<!-- 32-bit exe without LAA will be limited to 2GB by default --> of RAM.
** Historically, {{hl2|3.1}} and {{hl2lc|3.1}} had a [[w:64-bit|64-bit]] update in 2005, but it was later removed likely due to instability on some systems at the time. {{Csgo|3.1|nt=CS:GO}} later received an [[w:64-bit|64-bit]] update in 2016 for Mac and Linux systems. On April 19, 2024, {{Tf2|3.1}} was upgraded to [[w:64-bit|64-bit]] on Windows and Linux. All other {{src13mp|1}} games ({{css}}, {{dods}}, {{hl2dm}}, {{hldms}}), and {{src13mp|nt=sdkshort|2}} have been updated to the {{tf2branch|1}}, adding 64-bit support to these games and the SDK Base.
* All code is written in C/C++ using [[Visual Studio]] .NET 2003 and later.
** [[Source SDK 2013]] code ({{tf2branch|2}}), can be compiled on Visual Studio 2022 (as of March 2025).
** [[Source SDK 2013]] code ({{src13sp|2|addtext={{nbsp}}branch}}), can be compiled on Visual Studio 2013 (as of March 2025).
** Linux versions are compiled using Valve's [[Compiling_under_Linux|{{code|vcpm}} tool]] (only relevant for {{src07}}) and the [[Compiler_choices#GCC|GNU Compiler Collection]].
* You can easily and quickly derive new entities from existing base classes.
* There is a internal context sensitive performance monitoring system
* Graphics performance measurement tools are built into the engine
* Modular code design (via DLLs) allow swapping out of core components for easy upgrading or code replacement
* The [[VScript]] scripting system allows using external coding languages (such as {{Sq|4.1}} and {{Lua|4.1}}) to be used in maps to create more complex systems {{l4d2|since}} {{tf2branch|also|addtext={{mb}}}}

=== [[:Category:Tools|Tools]] ===
<div style="float:right"> [[File:Hammer screen.jpg|thumb|340px|Screenshot of one of the Source SDK tools, {{hammer|3.1|nt=1}}, a WYSIWYG map editor.]] </div>

* {{hlfaceposer|2}}
** Facial expression tool used to craft speech and emotions
* {{hammer|2|nt=1}}
** WYSIWYG World editor
** Create [[Brush|world brushes]]
** [[Displacement|Terrain editor]]
** Place [[Prop|detailed world models]] and [[NPC|AI NPCs]]
** Set [[Navmesh|navigation points/paths]] for NPCs
** Place [[Tool textures (Source)|triggers, clip brushes]], logic, etc.
** Allows level designers to hook up I/O between entities to control AI within the game
* {{hlmv|2|nt=1}}
** Full [[model]] previewer
** Rotate models in any direction
** Able to setup hit boxes
** View physics hull
** View normals
** View the map in wireframe, shaded or textured view modes
* [[Studiomdl]]
** Model compiler
* [[VBSP]], [[VRAD]], [[VVIS]], [[VMPI]]
** Map compilation tools ([[BSP_(Source)|BSP]], lighting and visibility)
** VMPI - distributed compilation tool allowing level compiles to be spread across many PCs greatly reducing compile times
* Exporters
** [[:Category:XSI|XSI]], Max and Maya {{code|.smd}} exporters for exporting 3D models

== Branches ==
{{See also|[[Source/Engine versions]] - Source engine build numbers}}
{{Hierarchy|srcbranch_tree}}
The '''Source''' engine has multiple branches, each one of them adds new features and changes. New features added in later Source branches are generally incompatible with previous branches. For example, {{src13|2}}, which are derived from Orange Box branches, does not have any new features that the {{csgobranch|2}} had, and maps (as well as [[VTF]] 7.5 textures) made for {{as|1}} (up to {{csgo|1}}) will refuse to load in {{hl2|1}}, unless they are converted.

The latest Source engine branch is {{src13|3.1}}, which has three sub-branches: '''Singleplayer''', '''Multiplayer''', and the {{tf2branch|3.1}}. The Multiplayer branch has additional features not available on the Singleplayer branch. And the {{tf2branch|1.bold}} is the updated version of the '''Multiplayer''' branch, which adds more new features (from {{hl2|name}} 20th Anniversary Update, but also {{l4dbranch|1}} like [[radial fog]]), but it had incompatible [[WP:Application binary interface|ABI]]s, meaning that mods/tools compiled for {{src13mp}} may not work properly or simply refuse to work under {{tf2}} without updating interfaces. All first-party (Valve) games using the '''Multiplayer''' branch are now running on the {{tf2branch|1.bold}}, while games running on '''Singleplayer''' branches runs on more up to date version which have features from {{hl2|name}} 20th Anniversary Update (except {{srcsdk13sp|1}} which still runs on older version of Singleplayer branch).

Games such as {{l4d|1}} to {{Csgo|1}} also introduce many newer features and graphical improvements. Both {{src13|name}} (SP & MP, and TF2) and {{Asbranch|1}} engines code are publicly available.

Some third-party games may also have their own engine branches, with many new features that are not available with any official Source branch.

*'''For the list of Source engine branches (including third-party branches), with notes about the branches, see [[List of Source engine branches]].'''

== Products using Source {{Table tools|Source_games}} ==<!-- DO NOT remove the underscore on this template, as it would break the edit, purge, etc... button completely -->
This is the list of games that uses the {{source|4}} engine.
<!-- To edit the list of the game, please visit the template page "Template:Source games" instead, then go to one of it's subpages there. Or use the edit button shown near the template itself-->

=== Products made by Valve ===
<center><small> [[Template:Source games/Valve|Click here to edit this list.]] </small></center>
{{Source games/Valve}}

=== Third-Party ===
Games, tool and mods made by third-party companies and mod teams.

==== Released ====
<!-- To edit the list, please go to "Template:Source games", or go back to previous page and click on the [edit] button on the year itself. List of games prior to 2020s are located in separate pages due to wiki limitations and to avoid long load times.-->
{{Expand|title=2004 - 2019|noborder=1|
* To see the list of third-party Source games from 2004 to 2019, check the [[List of third-party Source games]] page for more information.
}}
{{Expand|title=2020 - present ([[Template:Source games/2020s|edit]])|noborder=1|startcollapsed=0|
{{Source games/2020s}}
}}

==== In development (Unreleased) ====
This section are for unreleased third-party games and tools that have been announced, and it is currently in development, not publicly released, is in Beta/Early Access, or planned to be released.
<!-- NOTE: Sort the game by year if the release date is announced, otherwise, if it's was TBA (to be announced), sort by game name. -->
{{Expand|title=List of Source games currently in development ([[Template:Source games/unreleased|edit]])|noborder=1|startcollapsed=0|
{{Source games/unreleased}}
}}
[[:Category:Third Party Source Engine Games|More Third-party Source Engine games]]
* [[:Category:Source mods|More Source mods]]

== See also ==
* [[Wikipedia:Source (game engine)]]
* [[Source Engine Features]]
* [[Source SDK]]
* [[SDK Docs|Source SDK Documentation]]
* [[Source SDK 2013]]

== External links ==
* [https://web.archive.org/web/20110724220714/http://source.valvesoftware.com/ Official Website] (archived) - Official website about the Source engine
{{todo|How relevant and current these guides are? Keep links to current manuals instead of all at appropriate places. Use [[Special:LinkSearch]] for this.}}
* Source Engine Tutorials https://www.sourcemodding.com/tutorials/source
* Tutorials for Source Engine https://gamebanana.com/tuts/games/35
* Tutorials - Source - Mod DB https://www.moddb.com/engines/source/tutorials
* [https://github.com/ValveSoftware/Source-1-Games/issues GitHub Issues page] - for engine bug reports.
* {{Steamdb|tech/Engine/Source/|List of Source engine games on Steam - via SteamDB}}
* {{Wiki|Source_(game_engine)#Notable_games_using_Source|List of Source engine games - Wikipedia}}

{{Branch-navbox|nocat=1}}

[[Category:Game engines]]
[[Category:Valve]]
[[Category:Glossary]]