A City as an RPG

My usual group requested a campaign setting for D&D Next, and given our original DM's reluctance, I've been throwing together a gameworld. Given my love-hate relationship with Fantasy settings and running D&D in general, I decided to do something rather different with my gameworld -- let the players craft the world itself, while they learn the game's ropes.

Every setting has an ideal age -- a heroic age, where impressive feats and deeds are accomplished. Most of these settings also have thousands of years of intricate backstory, leading players through plot twists and simply letting people who read accept the events as part of a larger background. This is singlehandedly the reason I avoid established settings -- there will always be a player who's read more, and there will always be questions with lore answers you aren't familiar with. There is one exception to my "established gameworld" rule, and that's Vampire: the Masquerade, simply because I spent so much time consuming the vast metaplot.
Rather than letting my players be told about the rich backstory, I want them to play through it, and see events unfold before their eyes. I also want players to have a hand in these events, to the point where they feel particularly attached to the setting's background. My final goal is to have their actions during these events define the Heroic Age that they will eventually play in.
Ideally, I'd want to break up each major backstory "event" into a 3-session arc, with premade characters for players to get a feel for how each of D&D Next's classes work. Over the course of each session, they make pivotal choices in a manner similar to how The Walking Dead plays out -- forced choices about which characters live and die. I'd also like this to influence how technology develops, in a manner similar to a Civilization tech tree.
I also want the players to see the lives they helped direct in the mythology of the gameworld in the same sense that Odysseus, Aeneas, Achilles, and Hercules each took on their own stories, while the tales themselves twisted and shaped the societies that grew from them. I'll likely post developments here. In the meantime, here's part 2, outlining the concept a bit further.