#1: The base ingredients. What do we know about the Firefly universe? Interstellar travel, psychics, cannibals, and legalized prostitution.
#2: The spices. Q1: What does Firefly feel like? A: Old West. Q2: What’s fun about Firefly? A: The language, sharp-shooting, wild stunts with spaceships, Kaylee.
#3: Mix until smooth. So, what we want here is a workable plot line which fits in the ‘verse but doesn’t feature any of the main characters. E.g. — playing as Luke Skywalker is lame, but playing as Kyle Katarn is awesome. We’ll set this in the post-unification, pre-Serenity timeframe.
You play as a newly-recruited Alliance agent who is sent undercover to gather up a young woman from a far-flung dirthole planet. You book a seat on a civilian transport (NOT the Serenity) and head out. You have some adventures on the way there and get to know the crew.
Once you get to Dirtonia, you discover that the woman you have been sent to bring in is a Companion, and a psychic one at that — which makes her wicked good at her job. The Alliance wants her for the River experiment. You, being a good guy, decide to go rogue.
The overall plot pits you against an Alliance bigwig who is oppressing a dusty planet known for harboring Browncoats during the war. You and your ragtag band of misfits (you end up Captain, due to some serendipity) free the locals from his reign, cleaning up the single-horsed town.
Gameplay switches back and forth between rpg-action and flight-sim (reavers are out there). You meet up with various lesser characters in your travels (e.g. the Serenity’s original engine guy — you know, blonde tattoo dude? — is on your crew.) and hit some of the locations from the show. Lots of shooting, quipping, and Blue Sun cola.
Joss? Call me.