Crepuscular Rays in Screen Space
I have added a new post-processing effect that approximates light scattering on the sunlight according to this GPU Gems 3 article. It required a minor coding on the engine, I have introduced two new built-in shader parameters: sun screen-space position to use in the calculation, and a term that gradually scales down the ray effect when the camera is not turned towards the sun. The process itself has been implemented in the postprocessing shader of the deferred chain, that made implementing it easy because all required data is available at this point of the rendering.
Here are some pictures about the result.