Yeah, that Dwarf Fortress hack of Polaris? I may post about that someday. Maybe.
At the moment, I have a thought: when someone asks you "What's your game about?" they're really asking (or you should really be thinking) "What happens in play, independent of/because of the rules?" Sometimes you will answer the first question one way, and the second question in a very different way. And, of course, sometimes the game ends up focusing on different things for different people.
For example - Kagematsu. The author tells you, quite explicitly, that it was a game written to capture that feeling of petty competition between women over relationships, and the way that women are often socialized to be pointlessly judgmental of one another.
When I played it, it was a game about flirtation, awkwardness, and sexuality. Gender entered into it, sure, but not much - the deference and awkward pauses had as much to do with status differences as they did with feudal Japanese gender roles.
This also ties into what the "fruitful void" is all about - you cannot see what a game is really, truly about until you have played it. Even then, some games require at least a couple of sessions before all their different things can display themselves.
Kind of like how after a few Advances, your Apocalypse World character is just no longer likely to fail at things s/he's good at, anymore, meaning that hard choices are not presented to you as often anymore.
So - the point is this: why not try starting out with what kind of play experience you're envisioning? This can be tough, and pretty abstract, but at least at some point in the process, you're going to need to know/decide/imagine what play itself should look like. This goes far beyond the genre, the setting, mechanical ideas, even player roles. What kind of stuff happens in play? What are we doing? Build from there.