Worldbuilding: Pure Bottom-Up Worldbuilding

Since I'm in the process of editing my draft of Thorn II and working on the rough of Murder of Mages II, I clearly don't have enough on my plate. 

At least, that's what part of my brain seems to think.

Because that part of my brain has become strangely obsessed with an idea of a brand-spanking-new-from-scratch worldbuilding project.  And by "from-scratch", I mean completely.

Whenever we do worldbuilding, there is typically some form of top-down idea guiding the process.  There's some underlying idea of what we want the world to be or have, the technology leer, the way the culture is.  We start from that concept and build down, forming the infrastructure to make that idea work. 

And there's nothing wrong with that.

But it tends to create limiting ideas-- secondary fantasy worlds that still are, in essence, England or Italy or Arabia or Japan in medieval or rennaisance times, or steampunked or otherwise tweaked.  The scent of the familiar stays with it. 

And, again, there's nothing wrong with that.  It makes it easy to define when it comes to writing stories.

But I've been thinking more and more about what really, truly working from the bottom-up would bring about.  That means starting with the land itself, building the details of geography and climate.  From there, decisions about flora and fauna-- especially the key domesticatible plants and animals, and then determining where the "cradle of life" where humans or other intelligent life emerges (indeed, if it's a fantasy world, the decision to have multiple intelligent species is crucial).  Once that cradle is determined, you would determine the pre-historic diaspora, as people spread across the world as hunter-gatherers before they start settling into agriculture.  And that's dependent on if settling into agriculture is even a viable option given their terrain and available possible crops.

From that point, the slow development of civilization and cultures as states and empires rise and fall, develop and regress.

Of course, the question is, would this be a valuable exercise?  Would the deliberate bottom-up process yield results that were significantly different than the more typical top-down one?  And more to the point, would it give a world that would be an interesting and dynamic setting for stories, or would it be little more than an intellectual exercise to its own end?

And is it a process a person can realistically do on their own?

I'm honestly not sure.  But I think it's worth exploring, and I'd love to hear other thoughts on the subject.