Valve used Source in many of their games in the following years, including Team Fortress 2, Counter-Strike: Global Offensive, Dota 2, and the Portal and Left 4 Dead franchises.

When it came down to show Half-Life 2 for the first time at E3, it was part of our internal communication to refer to the "Source" engine vs. the "Goldsource" engine, and the name stuck.Source was developed part-by-part from this fork onwards, slowly replacing GoldSrc in Valve's internal projects[3] and, in part, explaining the reasons behind its unusually modular nature.

The release of Half-Life 2: Episode One and The Orange Box both introduced new versions of the engine that could not be used to run older games or mods without the developers performing upgrades to code and, in some cases, content.

HDR rendering and color correction were first implemented in 2005 using Day of Defeat: Source, which required the engine's shaders to be rewritten.

It was mentioned again by Gabe Newell in 2006 as a piece of technology he would like to add to Source to implement support for much larger scenes that are impossible with strictly polygonal objects.

In addition, the facial animation system was made hardware-accelerated on modern video cards for "feature film and broadcast television" quality.

[14] Valve created the Xbox 360 release of The Orange Box in-house, and support for the console is fully integrated into the main engine codeline.

Multiprocessor support was further expanded, allowing for features like split screen multiplayer, additional post-processing effects, event scripting with Squirrel, and the highly-dynamic AI Director.

Portal 2, in addition, served as the result of Valve taking the problem of porting to PlayStation 3 in-house, and in combination with Steamworks integration creating what they called "the best console version of the game".

Both the OS X and Linux ports of the engine take advantage of OpenGL and are powered by Simple DirectMedia Layer.

[20] During the process of porting, Valve rearranged most of the games released up to The Orange Box into separate, but parallel "singleplayer" and "multiplayer" branches.

[23] There, Valve stated that it would be free to use for developers, with support for the Vulkan graphical API, as well as using a new in-house physics engine called Rubikon.

[26][27] Reborn was first released to the public as an opt-in beta update that same month before officially replacing the original client in September 2015, making it the first game to use the engine.

[citation needed] There are three applications packaged in the Source SDK: Hammer Editor, Model Viewer, and Face Poser.

Level geometry is created with 3D polygons called brushes; each face can be assigned a texture which also defines the properties of the surface such as the sounds used for footsteps.

Most third-party servers additionally run Metamod:Source and SourceMod, which together provide a framework on top of SRCDS for custom modification of gameplay on existing titles.

[34] Developed by Valve, the tool was originally used to create movies for Day of Defeat: Source and Team Fortress 2.