Red-eyed dust bunny
You're correct, the setting of GW1 is almost entirely implied. For example, I always got a lot of inspiration from the descriptions of the bots. I don't think the let's read really dwelt on that part, but those writeups suggest things about how the world of the Ancients functioned. But those are hints and suggestions; it's not spelled out.That all makes sense, but nowhere in your WIR has this ever been stated. In fact there is little in game stuff which is probably why I asked the question--that and a lot of people seem to really play up the post-apocalypse angle. Like what happens with kids who have mutation in small villages? Did I mention there seems to be little in game information?
The world itself is primarily defined by threats, curiosities, and artifacts. In other words, you only see the setting through the tools you're given to play the game, not by some holistic overview or a day in the life breakdown. There's a little discussion of population centers, currency, cargo cult quasi-religions, and a (comparatively) lengthy history, but that's pretty much it on the economic, social, cultural, and religious front.
Which can be frustrating, if you want everything planned out and defined. But it can also be wondrously (and terrifyingly) liberating. The focus on things you'll meet, problems you'll face, dangers you have to overcome, and the stuff you find gives the referee everything they need to start playing immediately. You have some powers, and there's a completely new world out there to explore. You don't need a setting bible or infodumps, because you don't really need to fill in anything, until it comes up.
This minimalist, bottom-up approach works best if it's highly reactive. Who cares what's over the next hill? Nobody, it's irrelevant -- unless the players are interested. In which case you invent it, and move on. Which is the best way to handle a game of exploration. Let the world emerge not based on some grand vision you have, but on what the players are interested in. It does require some improvisational skill, but it also reduces the workload because you only really need to think one session ahead.
You can also pick up a lot of cues from your players. Their questions, how they phrase them, the implied assumptions they make about the world works -- run with them. Let them, perhaps unknowingly, create the framework for a world that interests them. For something like how they grew up, ask them. Only then figure out whether everyone's a mutant, whether they had to struggle, whether everyone liked them, and so on. Then riff on it, emphasizing those themes -- for instance, if they're unique and special and everyone likes them, they might be the chosen ones in some mysterious prophecy. If they're persecuted, you could make some dramatic betrayal or expulsion (though that's probably for older kids). And so on.
Another advantage of this approach is you can easily see what works, based on how the players react. It's not a white room theoretical exercise. If they're interested, they'll ask questions and follow up. If they're not, just drop it. Your job to is leave hints and hooks, and then flesh them out based on their reactions. Don't invest a lot of work in creating the hooks, just spin them off until something catches. If they don't care about the prophecy, then there's no reason to ever bring it up again. If they do, then put some effort into developing it.