VK9: Direct3D 9 compatibility layer using Vulkan
D3D9 is my all-time favorite 3D API. It was at that sweet spot of being powerful enough that you could do stunning things with it (the Xbox 360 generation is effectively D3D9-level hardware), and it was simple enough that amateurs and hobbyists (and high school kids, as I was at the time) could dive in and get stuff on the screen relatively quickly. D3DX had some handy helper libraries for loading models, doing transforms, and loading textures. I get the benefits afforded by subsequent iterations, and nowadays Vulkan and D3D12, but their interfaces are so optimized toward specialists, and it would be nice if more was in place to cover that middle ground use case between "I don't need a full-on 3D game engine, but I don't need to worry about low level GPU stuff either." Of the new APIs out there, I feel like Metal is the only one approaching layperson usability, and it's trapped in the world of Mac and iOS. Of course you can stitch together something that looks like an open source equivalent of the old D3D9 SDK yourself from things like glm and AssImp, but it's nice to have all that in one package.