So, basically, the Mysterious Island, in space, except not? Cool idea!
No Playbooks, just Roles
You start character creation by choosing your primary and secondary roles from a list (e.g. command, science, pilot, trader, pirate, convict). Primary roles should be unique. Secondary roles can be duplicated. Your roles dictate your starting stats, as well as any equipment you were able to salvage from the wreck, and a number of NPC's who have survived (with the ability to detail a few of those closest to you).
I have seen this done already in several different ways (Props to Uncharted Worlds) and I think it is fairly interesting that many space-themed PbtA games seem to go for that kind of solution. I am also trying my hand at a « split playbook » right now and I have some questions:
I wonder how you plan to deal with stats ? Do you split stat distribution evenly between roles ? Do you make one role distribute the stats ? Do you instead make a "free" stat distribution, decided upon by the player according to "how the stats balance"?
How many primary and secondary roles will you try to support ? A set number ? More than 5 (E.g, more than the usual "high" amount of players)? Do you want to see some roles be taken by some players every game or does it not matter ?
As an aside, I am intrigued by your decision to duplicate secondary roles. I think the « only one player for each playbook » really adds to the game. Any specific reason for that
breach of protocol ?
Going Native
One of the central themes of the game, though one that can be avoided in part or in total (at least for a while) is the act of going native. As you learn to survive; you sharpen the skills that keep you alive and relegate the trappings of civilization to the past.
I also wonder about this. Do you wish for your players to be naturally inclined to go that path or do you plan to allow them to pull a "mysterious island" on the game? It is notable that in the book that, I think, inspired this trope, the characters do not ever actively adapt to their environment. Actually they do not change much at all. What they do is that they use their "civil" knowledge (Mathematics, Astronomy, Chemistry...) to transform the environment into a much more friendly one for them. Adapt, and not get adapted.
I think allowing this may create some interesting situations. You obviously want the balance between "civil" and "native" to play a large role, and as such the very possibility of an "all civil" approach may seem threatening to your design. Besides it may introduce a fair bit of "status quo mining". However I'd argue that an "all native" approach would be threatening to your design as well, and in much the same way. If the players are eventually all forced to go native, then there is not much struggle between "native" and "civil": Native is the only answer and the only question becomes "How do they get there and loose the bearings of civilization"? The new status quo players contend themselves to being "perfect adaptation".
Now say you have a limited class pool, in which less than four characters profit from being "civil" (Scientist, trader and captain, for the sake of example) and less than four characters profit from being "native" (Soldier, Pirate and Convict.). You now have a system in which, in a 4+ player game there is designed imbalance. There will always be at least one player that will try to push for the opposite of what the other players desire, which might just be the force you need to drive the game forward.
Granted, this has the obvious drawback that your game becomes designed for "4+" players, and may only have 6 playbooks total. Yet maybe this is something you can get around with your primary and secondary class system and some clever mathematicking. Ah well, just some thoughts.
At any rate the idea is very interesting and I'd be curious to hear more!