Hey all!
I am preparing a west marches like game set in space! But compared to classic fantasy adventures, I feel a bit overwhelmed by the scale of it all. Do I have to have a hex map of every planet? Factions for each space station? Even within the confines of a single star system it feels like the prep is endless.
So I wanted to ask all of you how you would prepare for this kind of thing. And if you ran something like this before, I want to hear how it went!
Thanks 
I ran a game like this recently. I mostly tried to generate the world as we went along. I used Stars Without Number, and made heavy use of it’s procedural generation tools. Here’s what I started with:
-A map of the solar system (my campaign took place in one crowded system with no FTL, you can simply scale this up to a star map for your campaign)
-Around 6 major planets or other locations, with a few factions and specific locations (like cities) for each. I didn’t go deep into detail here.
-An initial adventure to start the party out.
-A few rumors or prompts for the party.
At the end of each session, we would discuss what the players wanted to do next, then I would generate the needed locations before the next session. This kept prep to a reasonable level.
There were times where I’d run from a module (I converted A Pound of Flesh for example) or the party would spend many sessions exploring a single location I prepared. In both cases those worked as little breaks for me, vastly reducing the amount of prep I needed to do.
Hopefully this helps you out!
That is a noble undertaking! I tried to but fell flat as I just took on too much trying to detail everything in advance. What I learned. Next time I would use the Stars Without number tools to create a single sector, that is more then enough to start with. Using this https://sectorswithoutnumber.com/
For something lighter or in addition I often reference EotE Alphabet | Triumph & Despair its good but of course with certain assumptions backed in. I often use Planet Generator by Zarkonnen for ideas and maps/images when prepping normal games.
You can also let players do some work if you utilize Beyond the Wall /Further Afield methods to let them add locations to the star map. Hope some of this may be useful to you.
Ok, I am biased. Huge Traveller’s fan here!
Stars Without Number is a huge toolkit for space sci-fi campaign, but I prefer the open source iteration of Traveller that is Cepheus Engine. There is a whole chapter dedicated to sectors and planets generation! You can roll it or use the online generator.
And you could use the tools of Traveller Map to build posters and booklets!
I’m running a sandbox using Mothership, but I took a different approach to you. I’ve used a space station (Prospero’s Dream from a pound of flesh) as a hub or home base, and the crew/players are doing jobs and exploring the surrounding space. I’ve set it up, though, so that the station is the major centre of population, and most of the rest of the hexes are small planets, small space stations or just populated with some random event (merchants, pirates, asteroid field, em storm etc etc). Small stations are either independent (random population e.g. religious sect, merchants, pirates, prison colony, research outpost etc) or affiliated with one of the major factions in the sector (the factions in a pound of flesh, inscrutable androids associated with The Deep from gradient descent, a religious group and a pirate gang) in either a major (it IS that faction) or minor (they’re associated with the faction) way. Planets I haven’t finished making my generators for yet, but will either have small colonies/outposts of random affiliation, be barren or have life (no sentient life in the galaxy other than humans… Yet). Amongst all the random stuff I have dotted about modules from mothership to either stumble across or to be mission locations.
Aside from not having sorted out planets yet it’s working quite well. The sector is sparse so most encounters are other ships or astronomical events. The players have been focussing on doing stuff on the station or taking jobs so far so haven’t landed on a planet yet (which is good since I don’t have a plan for that yet!) and don’t seem to mind the sparse sector (or at least haven’t said anything!) They also don’t seem to mind the unrealistic astronomy of the map - I’ve got no ability to generate what might be a realistic seeming “landscape”, so I just focused on what would be fun to play in and would fit the setting (i.e. tone of the game, level of technology, degree of human diaspora etc.)
I think for space stuff it pays to focus more on factions, and Points of Interest rather than attempting to map evvverrryyyythhing, points of interest style setup also works well for if you want to expand things later. I would sketch out firstly the broad factions that hold sway over multiple places (because they will keep showing up, and you’ll be able to spin off smaller sub factions and cool ideas once you have them established) and then just go as simply as possible, just writing one or two bullet points of inspiration for each planet/star system/station.
Then, once you’ve got a base like that (and tip, go really wild with your base inspiration, don’t focus too hard on making things make sense or click together at first, that’ll come later, and having a base of often weird and incongruous stuff will give you a lot to work with) so once you’ve got the base, you can go back through and further develop points that capture your imagination or that players are investigating.
All in all go for maximum evocativeness with minimum words. Stuff like…
Trembly’s Station -
This is excellent advice. I concur on focusing on factions and points of interest as a good starting point. Think of all the things players will interact with in the first few sessions - sub-locations (points of interest on the planet, space station, etc) , npcs, factions, and flesh those out enough to get through a couple games. Then as you expand out, use more of an outline structure. You can document what other planets are in your solar system as needed (probably just a name to start) and as you continue expanding references outward, just write those down. Things can exist in a quantum state of both existing and not yet really being fully rendered. It would be a lot of work to design an entire galaxy before play, so let that stuff emerge from gameplay. View things that are farther away in more of a rough outline/sketch that you can further detail as you need.
My group ran a space sandbox for about a year. Our game ran heavy on character goals so we seeded much of the solar system with their backgrounds. I made up a handful of factions with summary blerbs and encouraged the players to flesh out bits they were interested exploring. This is a major point IMHO, leverage your players as much as possible for sand box. If they are not into contributing then question if you should be running a sandbox.
Location / Faction Generation
What major thing it is known for?
– Keep this simple but evocative (ex. powerful corporations, desolate way station, cute wildlife)
List of rumors.
– Have your players help write these. This will set the desired tone.
List of notable figures that everyone knows.
– People that are known usually have employees which equals more NPCs. They also have enemies.
Thematic list of moments to be pulled from when the players falter to keep the action moving.
– Make these specific to the vibe you want the location / faction to have.
These are some steps that I took away after running the campaign. I prepped light and improvised like a maniac. Not for everyone. Give your players the ability to describe all the mundane things and name every NPC. The shared brain space will be a boon. You never know when that docking attendant Erlich Rayboots will be handy to throw into an underbelly tavern brawl.
Also make lore entries periodically as events wrap up. As always involve your players with this stuff. These can become troves of good ideas to link back. The impact your players will feel while interacting with the stuff they made is solid. Especially when you surprise them with a deep call back or unexpected twist. Guess what, Erlich Rayboots is under cover for the General Alliance and is investigating you.
Last bit is your entire setting is useless if it does not complicate the character’s life in a meaningful way. In space sandbox I enforce things like legal violations, media coverage, debt, and supply logistics. These details matter way more than how many space stations you can name in a given star system and who controls them. The players make a wrong step with the law. Ask them who do you go to for help? That answer will write your next NPC. It is just up to you what that NPCs help will cost.
Anyways have fun!
Thank you so much everyone! This is all very helpful advice. I think I’ll start by focusing on a main hub for the players and scatter around some points of interest with short descriptions + a couple major factions. The note about relying on player feedback is great, I’ll use it during the sessions for sure.
I created a system for this, but not sure what kind of game you’re running. It’s designed to be low/no-prep, and includes lots of guidance for new players and GMs (and online tools if you’re running on Zoom). Free, too.
But right now, I’m chasing all those other crazy links … wow …
Thanks for the link! I think i’ll glean some procedures from your system 
I am a teacher. We are similar to pirates. The motto is “beg, borrow, and steal!” 
Feel free, and would love to chat more anytime.
Besides, the advice above, another question would be: is there any FTL or jump drive in your campaign? How travelling works? In sci-fi gaming, this could change how players approach the space of the map.
For now I’m working with a single star system! In the lore, jump drives are rare and expensive. Travelling from planet to planet takes days. Kinda want to emulate trad fantasy travel from city to city.
Holdfast is on my agenda to run locally sometime. Maybe in January if not before. (Busy calendar!)
I strongly recommend to think carefully about it. It’s a game changer regarding how and at what pace the chracters’ll interact with the hex map.