I imagined it as the next PCP. So, "collaborating to write a history of an alternate earth" is what I envisioned.
This is what I was envisioning as well. My want out of this game is to come up with a world that has a rich history and diverse cultures. I'm really looking forward to the interaction between civilizations and watching their rise and fall. While I don't mind a game like DoW, I think we've already summed up why that might not be a fit for this particular setup. For me, DoW seems more limited to the creation of a continent although that could just be because that's how we've played it in the past.
As for needing points for a turn, I don't think that's required. I'm pretty sure we all have a good understanding of our 'scope' on what we can change in a given time period. This game is going to center around collaboration and working together and I think we're all in a good position to call someone out if they're overstepping their bounds (in a nice and productive way). Any disagreement can be voted on by the group with a simple majority to decide the matter. We've already been doing that informally with the ground rules, so I don't see why we can't continue it into the game.
However, we might need to have a more concrete system around conflicts between cultures/civilizations. That's an integral part of history and I think there are many examples were chance plays a large role in the outcome of a conflict. It would also be nice to have a more concrete system since I doubt everyone is going to be completely open to having their creation conquered by the neighboring people, especially if said people are prone to scorched earth policies. I don't necessarily have a good suggestion right now, but I'll try to think of something. Unless we want to approach it differently?