The idea of 12K (11520×2160 resolution) gaming is nothing new. Even Microsoft has been talking about it for a couple of years now. But it's one thing to demo it as some pie-in-the-sky ideal of a brighter future, and another for an actual game to officially support the ludicrous resolution at launch.
That game is Project CARS, and while there's no such thing in 2015 as a 12K monitor (even 4K monitors are rare), the support is there on the understanding that some maniac, somewhere, will own three 4K monitors and string them together
The game actually demoed this support back at E3 (and CES) last year, as part of an Nvidia showcase, but that was for E3 (and a graphics card company to boot), where "realistic expectations for home use regardless of personal wealth" and "video game visuals" rarely intersect.
Since the actual game will officially support it though, it will be interesting to see real humans in the outside world owning a rig with three 4K monitors (which is probably not you or me) be able to try this out.
Here's what that demo looked like, if you want to suddenly feel inadequate: