Yeah, I'm not sure about 'cultural' maybe, but it has to speak clearly to a specific vision. You can't make a PbtA that is like "generic space opera", you need specific tightly drawn character archetypes, a tight agenda, etc. that all fit together. Like, I could see a PbtA that would reproduce the sort of "Classic Traveller, we got a Free Trader, we're just booting around trying to make rent." sort of game. It would probably NOT do other sorts of Traveller games, like Mercenary Dudes, or something like that.