No player has a real grasp on 40k lore or background, except for playing Dawn of War series games. I've decided to take advantage of their lack of knowledge and likewise make their characters have a similar problem as well. The idea has a few kinks, but i think can sneak by mostly unnoticed.
The characters start trapped in a warp-locked star system, that has acted more or less, as a dynastic tomb for the RT legacy. 500 years previous the dynasty embarked on a great endeavour to colonize a world in the Expanse, investing heavily only to have the warp seal them away. Shortly after the game begins the warp will settle and the players will be able to leave in a mostly depleted vessel back to the Calaxis (sp) sector to annouce their survival - and subseqent reconnection with the rest of their dyntasy.
The player RT will start third in command, in short order his father is murdered by the eldest sibling who has become tainted by chaos, quickly promoting the players up the chain to their proper places as leaders. On this point I'm not clear, but I would like to put the older sibling in-charge of a grand-cruiser (the specifcs aren't important), and turn him into a recuring chaos-villian and a fleet of chaos raiders. The players have to flee the system in a smaller vessel avoiding him.
That is the major plot line, not intended to be overly long, but enough to introduce some concepts.
Before the warp settles, there will be opportunity to complete endeavours related to a proper RT game (ie. valuable equipment, the colonists, the resources that have been collected, Imperium factions still represented, etc).
For extra cynicism, I've consider making the RT dynasty the Haarlocks from Dark Heresy: when the players do make it back, they discover the entire dynasty has been wiped out by itself, 200 years ago and the warrant is almost forfeit. Which will seguway (sp) into an encounter with the Inquistion that offers them the opportunity to "free up" the red-tape locking the warrant (and coincidently their ship) in legal disputes for decades, providing they complete a couple of jobs, while the Inquistor "helps" them out.
I've considered, just for fun having an Ork on the player (not a player), or a minor Ork ecosystem in some long abandoned part of the ship.
Thoughts?