The introduction below to the 40k universe has been lifted near verbatim (with only rewording of the last paragraph) from the introduction to the Rogue Trader Role Playing Game core rulebook and is not by my hand.
It is the 41st Millenium
For more than a hundred centuries the Emperor has sat immobile on the Golden throne of Earth. He is the master of mankind by the will of the gods, and master of a million worlds by the might of his inexhaustible armies. He is a rotting carcass writhing invisibly with power from the Dark Age of Technology. He is the Carrion Lord of the Imperium for whom a thousand souls are sacrificed every day, so that he may never truly die.
Yet in his deathless state, the Emperor continues his eternal vigilance. Mighty battlefleets cross the Daemon-infested miasma of the warp, the only route between distant stars, their way lit by the Astronomicon, the psychic manifestation of the Emperor's will. Vast armies give battle in his name on uncounted worlds. Greatest amongst his soldiers are the Adeptus Astartes, the Space Marines, bioengineered super warriors. Their comrades in arms are legion: the Imperial Guard and countless planetary defence forces, the ever-vigilant Inquisition and the Tech-Priests of the Adeptus Mechanicus, to name but a few. But for all their multitudes, they are barely enough to hold off the ever-present threat from aliens, heretics, mutants- and worse.
To be a man in such times is to be one amongst untold billions. It is to live in the cruelest and the most bloody regime imaginable. Amongst the most powerful of mankind are the members of the D'Romas Rogue Trader dynasty- they are explorers who have authority and freedom far beyond the comprehension of the masses. Empowered by an ancient warrant of trade and warp-capable ships, they venture into the uncharted voids, discovering new worlds, lost civilizations, and bizarre alien technology. Fortune and glory are theirs for the taking. The dynasty and its scions stand on the threshold of unlimited opportunity and innumerable dangers.
