I've written much about the Dark Nebula, both in 2014 and in 2018. However, this setting evolved in the meantime, and it is high time to present a coherent, consolidated setting overview. I have also made some changes to the setting, reflected below.
Real-world work constrains permitting, I will continue developing this setting on this blog in the following days and weeks for your enjoyment and for my own (prospective) Solo game.
The Long Night has Come.
The Ziru Sirka, mighty empire of Mankind, ruled the stars for millennia. Suffocated by bureaucracy and drowned in a quagmire of bureaucracy, this magnificent culture was rotten at its heart. Its Terran conquerors, despite their heroic efforts, could not save it from its inevitable doom. Thus the Rule of Man - a bright light among the dark stars - fell into oblivion. Many worlds died in isolation. Others fell prey to raiders, pirates, and slavers. Chaos reigned.
This is the darkest hour of Humanity.
The year is 2900 AD - later generations will call it -1619 Imperial. The 30th Century has just begun. The Long Night reigns for 157 years. The Rule of Man is no more. But on the frontier, far from the worst parts of the collapse, a new candle flickers in the dark. A candle at Maadin, an old colony of the Second Imperium. With its rise from the ashes of the old empire, it built a confederation of nine worlds - the new Maadin Confederation.
However, a new power arose to challenge the scattered human colonies of the Dark Nebula - a young alien species, proud Aslan. Entering the scene five centuries ago, the slowly rose from their homeworld to a union of several worlds - the Aslan Heir ate. Its Trailing expansion, however, encountered human resistance from the various pocket empires of the day, and thus most of its colonial efforts are to the Spinward. Cold peace endures between humans and Aslan, disturbed by brief periods of warfare.
Now, once more, a war is brewing. The Solomani Confederation of Maadin thirsts for resources while the Aslan thirst for land; slow recovery from the initial collapse means that heavier military forces are once again available.
But as the two polities maneuver in preparation for war, the stars of the Dark Nebula, long absent, have reappeared. Now, they are the key for victory - or possibly the doom of both prospective belligerents.
A Note on Canonicity
Dark Nebula is not canon. I repeat: it is not canon in any way. It is vaguely set in the OTU, but in a variant OTU. Specifically, I use material and even CT adventures in a way suiting this particular version of the setting, sometimes in ways which are very different than those of canon. That is, some adventures set in the Solomani Rim, the Spinward Marches, or Foreven are placed on this Dark Nebula map, and so are a few alien species, locations, and artifacts.