DirectX 12 is the latest iteration of Microsoft's well-known and well-supported graphics API. While this is proprietary for Windows PCs and Microsoft Xbox game consoles, these systems obviously have a wide install base of hundreds of millions of users. Furthermore, a variety of GPUs are supported on Windows PCs besides NVIDIA cards, and the Visual Studio IDE provides a great ease of use. DirectX 12 actually supports low-level GPGPU programming-type concepts and can utilize multiple GPUs.