And then: Black Sun Deathcrawl
".. the apocalypse is not merely nigh, it has passed, the world is over and all that is left are the crumbling ashes of the ages before and the Cursed survivors who have yet to succumb to the soul-obliterating rays of the Black Sun. Make what you can of the little time you have left before the Black Sun renders your efforts meaningless."
The GM's introduction, or mood-setting section describes a little of the worlds past and how this came about. The PCs and their universe have more or less been sacrificed in an effort to keep those of The Bright Sun safe (but it may yet fail them).