No worries I enjoy playing whenever you can
Now this is all a matter of historical record, and to some extent myth to me, as it has been about 10,000 years since they ended, but I'll try to tell you.
[ Gaunt takes a breath. ]
The petty dynasts and warrior-kings of Terra murdered each other in the darkness of Old Night, worshiping dark old gods and using sorcery of various sorts on one another, along with hordes of techno-barbarian reavers. Humanity was on an inevitable road to decline.
Until one man stood up. The God-Emperor of mankind. He created an army of genetically modified super-soldiers, later known as the Legiones Astartes, unified Terra, cast out the old superstitions and spread mankind's reach to their scattered colonies among the stars.
While later one of his own sons struck him down and placed him in an eternal state of near-death, imprisoned on the Golden Throne of Terra in the center of the Imperial Palace, he still psychically powers the great beacon of the Astronomican, and watches over every human soul, protecting them from the Ruinous Powers of Chaos. In return, we offer him our fealty, worship, and devotion.