Think Spore.
Now, think about doing every aspect of life procedurally, from the largest star-forming phenomenae to the culture of some obscure alien society to every blade of grass to the system which forms that blade of grass to the seeding of that first blade of grass to the smallest level imaginable. No, that's not spore, that's a shitload more complex than spore.
It's an idea I had and spurred me to start learning programming languages again (i barely have any time available and spend maybe 4 hours a week trying to learn BASIC right now though, lol...) and, like every other idea I come up with, I go do stuff relating to it for a week only to have my hopes utterly crushed to discovering someone's already doing something a lot bigger on that... Oh well -_-.
ANYWAYS...Fable 2 is awesome, but 'Dmitri' is a helluvalot more kick-ass and has been in development waaaay before Duke Nuken Forever was thought up.
Here's a video, do the rest of the research yourself, I'm bored. Keep in mind this is from early 2k5, by lionhead (fable's devs). It looks better than crysis, with faster physics stuff than crysis. It's Crysis...in 2k5. Granted its on a really small scale....ah, well, look into it yourself.
http://www.youtube.com/watch?v=vGiPUx9Zgi0