Traveller!: A summarized history of the Third Imperium

First, there were the Ancients, who ran all over the galaxy dropping technology like so many godlike alien litterers, uplifting whichever species looked interesting, and - most importantly - spreading species to other planets. Nobody's sure why they did this: "Let's see what happens if we do this" appears to have been the motivation behind a lot of Ancient antics.

Then the Ancients up and vanished, as godlike beings tend to do (The Geonee say different but man, fuck those guys), leaving behind all their whiz-bang toys and genetic tinkering and various races they'd scattered across the stars. One of those species, the one that thrived and discovered the jump drive and first worked its way off the godforsaken rock where the Ancients had left them, was humanity. The humans of Vland, to be precise.

The Vilani (as they were called) spread across the galaxy, finding other inhabited worlds (including many inhabited by humans, which blew a few minds). The First Empire of the Vilani consisted of thousands of worlds, and at its peak explored technological reaches thought to have solely been the domain of the Ancients.

Then a bunch of jackasses who'd named their sun "Sun" came roaring off their equally-creatively-named planet, conquered the Empire, and proceeded to muck up everything. The Solmani turned out to be significantly worse at running an Empire than they were at conquest, and the so-called Second Empire was really just them riding what was left of the First into the ground.

Then came the Long Night, when warlords carved out their own fiefdoms, whole colonies on distant worlds died out, and it generally sucked. Fortunately, due to a metric shitload of diplomatic interaction and backroom dealmaking, the Imperium was resurrected under joint Vilani-Solmani rule, just in time to repel the incursions yet a third subspecies of humanity, the extremely psionic and super-creepy Zhodani Consulate.

Although this resurrection happened over a thousand years ago, the Third Imperium is still struggling to regain its former size and glory, engaged in border squabbles with the Zhodani, the occasionally belligerent Solomani, other human subspecies, and various aliens. Among the most notable no-man's-lands is the Spinward Marches, on the border of several empires and crammed with smaller federations, megacorporations and interest groups, all of which are desperate for a ragtag group of adventurers to provide them with various services