Beginning in the first half of next year, Feral Interactive plans to release software running on the Vulkan API. Feral is one of the three well known Linux port developers, the other two being Aspyr Media and an independent contractor, Ryan C. Gordon, who convert Windows games under some deal with the original creators.
They didn't claim which game would be first. Deus Ex: Mankind Divided will be initially released on OpenGL, but people are speculating that, since its rendering back-end is set up to efficiently queue DirectX 12 tasks, which is the same basic structure that Vulkan uses, Feral might release a patch to it later. Alternatively, they could have another title in the works, although I cannot think of anything short of DOOM that would fit the bill, and there has been nothing from Bethesda, id, or Feral to suggest that is leaving Windows. Maybe Tomb Raider?
Whatever it is, we're beginning to see more than just engine developers port software to the new graphics APIs, and on multiple platforms, too.