Epic Games founder Tim Sweeney predicts real-time photorealistic games will require roughly 5,000 teraflops, almost 150 times as much as today's fastest graphics cards (the Radeon HD 7970 offers 3.5 teraflops).
And while Samaritan's 2.5 teraflops (that's trillions of floating-point operations per second, laymen) is a far cry from the 10 megaflops that were needed to power the original Doom, we're still a good deal short of the 5,000 teraflops Sweeney calculates we'd need to process a fully realistic 3D scene in real time.
And even then, that would only handle the visual effects we currently understand how to model realistically—things like shadows, skin tones, smoke, and water. Plenty of the intangible elements of a scene, like realistic human movements, speech, and even personality, are way beyond our ability to model realistically just yet. "We don't have the algorithms, so even if we had a perfect computer today... we'd be relying not on more computing power, but on innovation in the state of the art algorithms," Sweeney said.