In case you don't know, you're in luck: there's the well-reviewed Firefly RPG (not to be confused with the panned Serenity RPG), and Firefly is basically confirmed to have been sourced from a Traveller game Joss Whedon played in college during the 80's.
> Firefly RPG by Margaret Weis Productions
Goddamn, Amazon is showing that selling for between $70-200! What's the reason for that?
If you're going in the LitRPG/Firefly-esque direction I'd recommend somehow getting your hands on this TTRPG book. It could possibly inspire some thoughts.
https://www.amazon.com/Firefly-Core-Rulebook-Margaret-Productions/dp/1936685329
No, a tabletop RPG.
Given you like scifi, and if you happen to like Firefly, there's a Firefly RPG and a tabletop Firefly: The Game.
FYI, there is a firefly RPG. /u/lollerkeet was probably referring to that, not to the board game.
I think that 'Firefly that was' is very good, but I can't really get behind a re-launch. It failed because it wasn't what TV could use. If it were to come back, it would have to be in some marketable capacity- which is not how the old show was.
I suggest you check out a few things to get your fix in the meantime:
Good luck and stay shiny!