Some ideas on how each player can contribute to building a world. It's all about relationships and broad strokes that the GM or players can fill in the details of at a later date-

Genre of Airship Pirates I view as swashbuckling therefore, each player could do the following-

• Plot
  • Who is your Arch Nemesis or Main Rival? Why?
  • Name at least three people you hate and why.
  • Name at least three people you admire or love and why.
  • There are 50 crew - establish relationships of some sort with at least 3 of them (not including any complications you already have) - this also means naming them. Ideally name them without consulting other players - I'm keen on getting rid of the media trope that every NPC must have a unique name
• Colour
  • Invent a religion (it's post-apoc and it's America, they would have millions of new religions). Maybe just a couple of sentences - and whether it was something your character heard of, knew someone in or actually was a member of.
  • Name a rival pirate ship and/or crew. If enthused, write up what they're famous for.
  • Invent a fantastical steampunk machine and your relationship to it. You saw it, had a friend die building it, aspire to steal or build one etc.
• PC vs PC
  • Establish at least two relationships between your PC and every other PC. Maybe something like “owes $10 for a bad wager in a dog fight last month” or “has been secretly short changing them when buying supplies for the past year in order to buy drugs”
  • Make up 5 aspects (short descriptive sentences) for your PC, and show them to the other PCs - Other PCs should prioritise them, add or subtract aspects, and write down the results for how their own PC views your PC.