Here are some rough ideas for a setting and for one of the factions. Let me know what you think. Suggestions/criticism/ideas welcome.

[b]History[/b]

It has been almost 400 Atheni-Standard Years since the Ignatio Event collapsed the Golden Road and two other major subspace arteries, plunging the galaxy-spanning Arcturus Imperium into two centuries of chaos and civil war. In many systems, oppressed xenos and undercaste humans erupted in rebellion against their now-isolated imperial sector governments, in others Imperial governors and admirals turned into warlords and bandit-kings, carving fiefdoms out of whatever territory they were strong enough to seize and hold. 

In ASY 3,320, Emperor Fashti XVIII was murdered on his throne by his successor, who ruled for all of three days before the Imperial Palace on Atheni II was bombarded from orbit by a rival claimant and all semblance of Imperial authority ended for good. 

The Galactic Dark Ages had begun. 

It is now ASY 3,576.

[b]Factions[/b]

[i]The Grand Duchy of Agamenos[/i]

Among the five stars and eleven inhabited planets of the Agamenos Sector, a sort of peace has been maintained over the last few centuries under the rule of the Grand Dukes of the august and ancient House of Kesselbrood. The succession of Dukes have fought off invaders and pirates, quashed rebellions, and steadily if unevenly improved the lot of non-humans, even allowing them representation in the Sector Diet. Thanks to shrewd leadership and luck, the worst of the Imperial Collapse left the Agamenos Sector unscathed.

The Grand Duchy maintains one of the most powerful navies left in the galaxy: archeo-tech Imperial ships of the line that have been lovingly maintained for centuries. Likewise, the Duchy can field a truly vast number of troops and xenos auxiliaries.

All is not well, however. The Grand Duchy has always been more of a confederation of states loyal to a dynasty than a unified polity, and the seams in its governing structure are beginning to tear. The current Archduke Adamantious von Kesselbrood XI is an enfeebled madman, governed by his ministers. Worse still, he is childless and a succession crisis looms. 

The price of safety has been stagnation. The army is massive but poorly supplied and commanded largely by incompetents. Neo-feudal economic arrangements have hampered industrial growth across the Sector while lining the pockets of a reactionary and short sighted nobility. Seperatists movements, meanwhile, abound among both monohumanist militants incensed at the relaxation of Imperial Caste and race laws, and among dissatisfied aliens populations, many of whom chafe at subjection to human rule.

[b]Other Faction Ideas:[/b] a transhumanist fascist, corporatist, or racist-democratic state who would be the Grand Duchy's main antagonist in the war. Lesser powers could be involved on either side, and are wide open for creation. Suggestions on all of the above welcome. 

[b]A note on subspace streams:[/b] these are avenues along which interstellar ships can travel especially quickly and energy efficiently. A galactic hegemony like the Arcturus Imperium depended on them, and the collapse of four major streams at once left many sectors cut off from the ability of the imperial navy to reinforce. They are not, however, the only means of interstellar transport. Subspace jumps outside of a stream are commonplace, but much, much slower. Many smaller subspace streams remain functional, and it along these that interstellar empires tend to grow.