Based on +Jeff Rients' 20 Questions about your Campaign Setting I've gathered some thoughts for how I see the Xenofringe setting working out. To reflect these changes the game is now called Arkbound.
For 99% of humanity The Tempest was the apocalypse. Every inhabited world was wiped out and left hostile.
Those living off-world were the sole survivors. Captains turned their lower decks into slums and expanded their one-hundred crew to tens of thousands. This is how The Arks grew into drifting kingdoms drifting through space.
What's the deal with aliens?
Strange creatures have been encountered and man has dabbled with artificial beings enough that some real horrors lurk the galaxy. Intelligent aliens have never been encountered. It seems we're alone beside our own creations.
What supernatural abilities exist and can science explain them?
Superstition and religion have found new popularity since the Tempest, especially in the Slum Decks of the Arks. Any actual psychic or superhuman abilities are yet to be investigated.
Where can we go to buy standard equipment?
Convince an Officer that you need something for the good of the Ark and he'll usually find a way to let you have it but send you on a suicide mission in return. Slum decks have an extensive black market.
Where is the best tech in the universe?
Technology advanced exponentially up until the Tempest. The best stuff sits abandoned on the hostile, flooded worlds.
Who is the most powerful being in the universe?
There are Ark Captains that hope to become Grand Admirals, but no fleets ever stay loyal for long. Whoever helms the most powerful ship is sure to find lots of jealous officers waiting for the chance to mutiny.
What do people do for work around here?
Arkbound do whatever they're told, from toiling on the engine decks to producing feeding slime on the factory decks. Only a tiny fraction of an Ark's crew are free Officers.
Where can we go to get some healing?
Much like engineers, medical personnel are likely to be Officers. There are places in the Slum Decks you can receive more questionable medical attention for something in return.
Can our bodies be taken beyond the normal human peak?
Bodymods and Stims are both established technologies, but often forbidden for an Arkbound. Uploading a mind to a computer was possible with cutting edge technology but no Arks have managed to reclaim that yet.
How well explored is space?
Space around the human worlds was well mapped and explored but unexplored space dwarfs that area.
Where can I hire mercenaries?
Most Arks have security personnel that can be corrupted to your service and fully fledged mercenary companies drift from one Ark to another.
What weapons do people use and who can own them?
People mostly own melee weapons and ballistic firearms not too different to today's weapons, but energy-based weapons have been salvaged from flooded worlds, as well as a few rumoured superweapons. Most Arks have little to nothing in the way of gun control.
Which way to the nearest bar?
Alcohol is typically distilled from waste products of the Factory Deck, so a bar is never too far away from there.
What's the deal with robots and AIs?
Both have existed for centuries in a huge variety of forms, from clunky and mechanical to nearly human-like. Most of the latter lie destroyed on flooded worlds.
Are there any wars brewing I could go fight?
Every Officer has a few enemies. Captains have even more.
How does space travel work?
Inter-system travel requires huge engines typically limited to the Arks. Smaller craft can be transported on these in return for their service but are otherwise limited to travel between neighbouring planets, typically taking a few weeks.
What is there to eat around here?
Arks are rarely able to support the growth of traditional meat or vegetables, so artificial food has become the staple. Typically it's unappetising gruel.
Any legendary lost artifacts I could be looking for?
Space is littered with the remains from the peak of man's achievement.