The 2nd edition of the Esoterrorists includes the Station Duty campaign frame, in which a Esoterrorist team is placed on long-term assignment to a particular small town for an ongoing investigation instead of the usual mystery-of-the-week. That approach also works in Ashen Stars. (The obvious worked example: Star Trek: Deep Space Nine swapped out the ‘planet of the week’ structure of the original series and The Next Generation for an ongoing plot involving Bajor, the Cardassians, and the wormhole aliens.)
Key questions to be answered, either by the GM or collaboratively with the players:
What’s The Scope?
Is this a single planet? A single star system? A group of systems? You could do as small a single city, or as wide as a whole cluster or outzone – maybe the station’s located at a crossroads in space where multiple translight corridors intersect.
Why does this place justify a permanent Laser presence? Is it strategically important – a choke point, maybe, at the mouth of a wormhole, er, translight corridor? Is it especially lawless, a pirate haunt that must be patrolled? Is there some vital industry here that must be protected? Is it a new government outpost that’s trying to return Combine order to the chaotic Bleed? Maybe this was the site of a major battle in the Mohiliar war, and there’s a scrapyard of wrecked warships here – or researchers investigating the doomsday weapons used by the mysterious enemy.
Who Are The Factions?
You need at least four or five major groups. What alien races are present? (At least some should be the same species as some of your more unusual player characters.) What major corporations? Nufaiths? Planetary governments? What are their attitudes towards the player characters and towards each other? Ensure there’s at least one conflict between every faction, even if they’d normally be closely aligned.
Possible factions include all the major Combine people (Human, Cybe, Durugh, Balla, Kch-thk, Tavak, and maaaaybe Vas Mal), plus the new peoples from Accretion Disk (boisterous Cloddhucks, drifting Hydrossi, corpse-stealing Icti, radioactive Ndoalites, fiery Raconids or shapeshifting Verpids); the various Nufaiths and Synthcultures, and the various political ideologies (Bleedist, Atomist, Combinism, Mercantilism, Empiricism and Racial Separatism).
Who Are The Criminals?
It’s a game about space cops, so stick in some space criminals. Having at least one established organised crime outfit (smugglers, illegal cyber-dealers, etc) and one bunch of space pirates or thieves is an absolute minimum. Which factions have ties to crime?
Who Are The Faces?
For each faction, come up with at least individual representative to give the players someone to talk to. Texture these characters by giving them a point of disagreement (possibly hidden, to be discovered by later investigation) with their own faction, and a connection to one of the other factions.
Also create a major location or headquarters for that faction, if one isn’t obvious already.
In addition to the arrival of the lasers, include some recent disruption to the status quo. This disruption might be something that lasts for the whole campaign (“the Combine’s returned to this sector”) or a plot arc that lasts for a few adventures (“space plague!”). Disrupting the status quo from the start lets the player characters become part of whatever new equilibrium is eventually established.
What’s The Station?
Is it a custom-built station? A derelict ship? A surface building? A moon colony? An old Combine military outpost?
The player characters still need a spaceship, as per the regular rules.
Wire Up The Arcs
The final step is to plug the player characters into the web of factions and plots. In a station duty campaign, there’s much more scope for long-running plots, so integrate player character arcs into the setting. If a player’s arc is “find my missing sister”, her disappearance must be closely connected to one of the factions or some location (maybe she vanished into that wormhole). If it’s “prove my worth”, then the character might become the leader or chosen, er, emissary of one of the factions.