I apologize this update seems to have created some confusion regarding D3D11, D3D12, and Vulkan. To elaborate on the questions from @Sense and @SpaceJay:
1) Infinity: Battlescape will always support Windows 7 as this is what we promised during the Kickstarter. Windows 7 support can come in two flavors - either D3D11 or Vulkan.
2) When the game ships to retail it will only support D3D11 so you can play on all flavors of Windows version 7 and above.
3) We will patch in support for our new rendering backend sometime after the game ships to retail. This will include D3D12 and/or Vulkan. As of right now the engine supports both.
4) I did the initial implementation of the new rendering backend using Vulkan with the hope that I wouldn't need to ever implement D3D12. Unfortunately Vulkan's shader compiler ecosystem is too immature and it quite literally doesn't work right with some of our shaders. This is why I ultimately decided to bite the bullet and implement D3D12. If the Vulkan shader compiler ecosystem improves by the time we actually decide to move the game over to the new rendering system then it will be patched to support Vulkan instead of D3D12 and D3D11 support will be completely removed since Windows 7 also supports Vulkan.
5) We need a valid implementation of D3D12 or Vulkan to validate the new rendering runtime as we build new systems on top of it. While it also supports D3D11 we cannot use D3D11 for validation because it lets you get away with doing bad things without telling you about it. D3D12 and especially Vulkan don't let you get away with anything therefore it forces your usage of the API to be correct in every sense of the word.