[quote=@Alfhedil]
Not overly familiar with Firefly's setting, so can't quite comment on that part for sure, but can say it's not as distant as the 41st millennium, nor as dark as 40K. 
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Thank you for that answer. One can hardly keep up with all sci-fi universes after all. 
I'll try to rephrase to get a bit closer to the core of my question. I am not a native English speaker, so I blame myself for not being clear enough. I could have done better. 
Explained briefly, Firefly could be summed up as "cowboys in space". Replace horses with space ships and revolvers with space revolvers and you're pretty much there. The series is filled with tropes from the great old western-movies but puts a sci-fi spin on them. 
You seem to have a grasp on the 40k-universe, where the last of humankind does battle against the powers of aliens, mutants and chaos gods, as well as each other. Each faction slowly declining and breaking down, most of them powered by already ancient technology. 
I'll add a third example for the fun of it. In Halo humankind has united against a common foe, the alien alliance known as the covenant. Focus lies heavily on the military engagements between humanity and aliens although a few specks of lore can be sighted every now and again. 

The themes of these three universes are almost entirely different, not only because the worlds are different but because of what they choose to focus on. In this game I already know that the focus will be a band of hired guns, but the world at large is still very much a mystery. Is it inspired by something in particular like Firefly and the old westerns for example?
You've also mentioned that we're hired by a corporation, which brings to mind a game called Mutant Chronicles, in this world corporations have taken over, and what we today know as countries and nations are either extinct or horribly obsolete. Corporations own land, military power, right of law and everything else that today's nations have access to but corporations as a rule does not. How would you say that the balance between corporations and nations looks in this game?