I think that the word "photorealistic" should be considered in a more philosophical way. The goal of games is to create an immersive and convincing environment

I think that the word "photorealistic" should be considered in a more philosophical way. The goal of games is to create an immersive and convincing environment but that does NOT necessarily mean that it would (or should) be indistinguishable from what a camera/eyeball would see if the environment were "real". If you talk with computer game artists, you will find out that they deliberately manipulate features, textures, geometry, distances, and colors in a way that is decidedly different from what would exist in reality. The purpose of this, ironically, is to make the environment more convincing (real-looking) to the player when the game is on. It is all about perception. I think that by looking at what is happening with computer animated films, one can get an idea of what will happen soon with computer games. It will certainly be possible to render an image at high fps such that it simulates with stunning accuracy what would appear on a CCD sensor if a camera were placed in a "real" scene. But then there will be deeper problems. Instead of worrying about the nitty-gritty of ray-tracing fidelity, game makers will be concerned with the same problems that photographers and filmmakers worry about: lighting, focus, focal length, lenses, scene layout. And then there are the well-known problems of "uncanniness" (http://en.wikipedia.org/wiki/Uncanny_valley http://en.wikipedia.org/wiki/Uncanny_valley). In other words, when you watch a great scene in a film with actors, it looks "realistic", but that "photoreality" is actually a very careful and deliberate fabrication-- it is not real.