I'm a big fan of Epic Games' Unreal Engine 4, as it's one of the most powerful, gorgeous engines that developers have access to. But this latest technology demo is one of the best, if not the best use of it I've ever seen.
Feel free to admit your mind is broken, and you don't know if you've just seen a movie with some added film blur, or a game engine. The developer behind it is from level designer and 3D artist Benoît Dereau, who worked on Dishonored. The Paris apartment is just totally gorgeous, and something I want to see come of this is an Oculus Rift-powered game with this level of detail. Insane.