CryEngine will be adding Vulkan to their 3D graphics engine. This information is based up-on a blog post on their CryEngine 5.4 (which would be released late next month). 

Actually on March 22, 2016, Crytek already announced a new version of CryEngine, called CryEngine V, which featured native DirectX 12 and Vulkan. Additionally, a new licensing model was introduced with a "pay what you want" model for usage and access to the source code. Vulkan BTW is a low-overhead, cross-platform 3D graphics and compute API and targets high-performance realtime 3D graphics applications such as video games and interactive media across all platforms. Compared with OpenGL and Direct3D 11 and like Direct3D 12 and Mantle, Vulkan can offer higher performance and more balanced CPU/GPU usage. Other major differences from Direct3D (prior to version 12) and OpenGL are Vulkan being a considerably lower level API and offering parallel tasking. Vulkan is also able to better distribute work amongst multiple CPU cores.

Back to Crytek, interested parties will be able to track the progress of this update via GitHub.

 "the team has been hard at work implementing a Vulkan renderer".

Following on from the renderer refactoring and DirectX 12 implementation, the team has been hard at work implementing a Vulkan renderer. The code can be seen in Code/RenderDll/XRenderD3D9/Vulkan/… although the feature is not functional, yet. We want to make these changes available to you for review whilst we are currently stabilizing the engine for our 5.4 release. So you can track our progress on GitHub until 5.4 is finally here by the end of July.

Crytek's Hunt: Showdown

Vulkan to be Included into CryEngine