DirectX 12 is Powerful Sorcery

DirectX 12: the technology even allows for calculating drying streaks of mascara upon the character's face in real time.

With the release of Windows 10 comes a very special API (Application Program Interface) called DirectX 12. This bundle of program routines, tools and functions lets programmers more easily access computer hardware directly, and to efficiently balance program code execution between multiple cores of modern CPUs (central  processing units - your computer's main "brain") and GPUs (graphics processing units). This allows multiple data streams of graphics, audio and simulated physics to be executed simultaneously, allocating it to hardware on an availability basis moment-by-moment.

The upshot for gaming fanatics such as thee and me is a tremendous boost in scene calculation and (rendering), framerates and visual effects.

To demonstrate the incredible power of this new "under the hood" software, hardware manufacturer nVidia teamed with Microsoft and Final Fantasy publisher Square Enix to create a real-time CG tech demo video. Real-time means the graphics were not prerecorded, as with a movie, but were being rendered frame by frame by the demonstration computer. This level of computing power has never been possible on consumer-level (as opposed to laboratory supercomputer) machines before.

Each scene in this demonstration uses about 63 million tiny mathematically-generated colored polygons - rendering on an order of magnitude greater than DirectX 11. Particularly impressive are the realistic hair, skin, and real-time lighting effects.

To render a scene with this level of detail at the resolution and screen size in the tech demo required the most powerful commercially-available hardware - four GeForce GTX Titan X video cards running in quad-SLI (parallel) mode with an Intel Haswell (i7 multicore) CPU.

That said, quality of this level is certainly within reach of consumers running smaller displays at home.
Spokesman Hajime Tabata introduces the video, noting that Square Enix is determined to achieve the "absolute pinnacle of quality" in computer graphics with Final Fantasy 15:

Although all modern 3D PC video games will benefit from DirectX 12, Wikipedia has listed ten titles currently in production that are specifically being developed for the PC using the tools and instruction sets from Microsoft's latest API, including Fable: Legends, Gears of War: Ultimate Edition and the newest in the Hitman series.