It needs to be said, but the way "3D" games are lit are already an approximation.

3D games do the left, while the right is only done with software renderers (eg POVRay, Blender)
And on top of that, there is also Caustics:
Both Radiosity and Caustics requires lighting to be calculated from the light source instead of at the viewer (the camera), so in a sense, the entire "scene" has to be rendered without any shortcuts to work. Hence not even the highest-end GPU can do this in real time, because that is NOT what 3D games do. 3D games are rendered "front to back" from the camera to the distance, so light can not be calculated to bounce off objects that there are not yet any pixels for.