AlenL SS4 certainly will not use the same version of engine as Talos does. It will use a _much_ improved version. Exact details will be revealed when SS4 is officially presented.

Talos will support Vulkan on Launch. SS3 not yet, but maybe later.

Article taken from GamingOnLinux.com.

Both The Talos Principle and Serious Sam 3 should be getting updates with the Vulkan API, and Serious Sam 4 will also use it.The same developer confirmed earlier than Serious Sam 4 will use Vulkan , but it won't drop OpenGL, which is nice.No word on a release date for SS4, and general details are very scarce so don't expect to hear more any time soon.They did share back in September that people who helped work on The Talos Principle were also now working on Serious Sam 4, so that's good news.Will be fun to see difference in performance with Talos on Vulkan vs OpenGL.