The IQGamer Crysis 2 demo analysis is on its way. But in the meantime I suggest you take a look at the video below. It’s a rather impressive demonstration of global illumination using the CryEngine 3 – using multiple light bounces rather than just one!
All the shadows and lighting, along with the actual rendering is being performed in real time. Although there is no in-direct shadowing taking place, there are other neat touches, such as diffuse shadows and HDR. You can also get a brief glance of CryEngine 3’s day/night lighting cycle.
Similar things can be done using pre-backed alternatives, which are obviously static – not great for scenes with noticeable changes in the lighting cycle - but cost far less, especially if baked directly onto textures themselves. Unreal Engine 3’s Lightmass solution springs to mind. It’s good alternative for games which feature a fixed sun position, relying on many local, dynamic lights to create a similar effect.
Crysis 2 uses a single bounce form of real-time global illumination: it's clearly visible in the Xbox 360 demo. But more on that shortly.