Strata Source engine branch

The Strata Source is a third-party branch using licensed Source engine code. It is a heavily modified version of the CS:GO engine branch with the Portal 2 engine branch's features ported, along with many major improvements to bring Source up to modern standards. Created by Strata Source, notable features include DX11 support, Source 2013 model support, Portal support, and more.

Features

Feature list from Strata Source's Wiki
New since CS:GO engine branch:

Native DirectX 11 renderer: Support for DX11 by default
DXVK support on Linux for both DirectX 9 and 11
64-bit support: Support for 64-bit. 32-bit has been dropped
PBR shading: Uses shaders to attempt to more accurately simulate real-world light
Ported Portal 2 engine branch features: Including but not limited to World Portals and Portal gun
Backwards compatibility with BSP v19-20, as well as native BSP v21 support
Backwards compatibiltiy with TF2/HL2 branch models: Source 2013 uses a different model format, now supported
.webm video support, replacing older Bink videos: Increased framerate, and easier to author
Many improvements to Linux support
Fully cross platform engine tools and utils
Steam Audio
Many improvements to the Hammer level editor
Many code quality improvements (Refactors, cleanup and C++20)
Sentry crash report integration