Funny you should say that ...
Is there an undeveloped setting that you'd like to see developed?
I've been working on a setting around the collapse of the Rule of Man, based in the area around the Daibei, Reaver's Deep, Magyar and Dark Nebula sectors. This could roll forward into the predecessors of the Aslan Border wars and the Reaver wars between the various Reaver states of this region and the Sylean Federation.
This was something I originally came up with back in the 1990s, and I've picked it back up as something to amuse myself with. I'm pretty sure I can see how to build it without having to significantly bastardise any existing canon.
The idea here is that this region was somewhat isolated in the Ziru Sirka period and was largely out of the way of the worst of the Terran-Vilani wars. It was a somewhat distant frontier region during the Ziru Sirka and was quasi-independent anyway, although somewhat under-developed.
Thus, the 2744 (whatever this is P.I.) banking crisis that brought down the Rule of Man had less of an effect on this region, and the presence of the Aslan to the spinward gave a significant impetus to maintain a working naval capability.
The core could collapse into introspection and infighting in relative safety as it was 50+ parsecs from potential aggressors in any direction. The spinward regions bordering the Aslan couldn't afford that. Thus, this region forms various states capable of maintaining a naval capability, who consider themselves to be as legitimate as the Syleans - if not more so.
This setting could go from the late 2700s (~1,700 P.I.) through to a Milieu 0 era, telling the story of the rise of what would come to be known as the Reaver states and the subsequent Reaver wars. You could tell it from the perspective of the Syleans bringing order back to the universe. Alternatively, you could tell it from the perspective of the Reaver states, who are quite happy with the status quo and are of the view that Cleon can stick his Imperium where the stars don't shine.
There are several periods that you could do, for example:
- Collapse of the rule of man - with a slightly post-apocalyptic feel. Parts of the old ROM forming regional coalitions, collapse of the Ramshackle Empire and rise of piracy and warlords in the absence of interstellar power "That sucking you hear is the sound of the biggest power vacuum in recorded history."
- Rise of the Reaver States (i.e. what would subsequently come to be known as such in Imperial history texts), surrounded by a post-apocalyptic wilderness to the Trailing side and by the growing Aslan threat to the Spinward. This setting would be maybe 2900-3000AD - a couple of hundred years after the collapse of the ROM. This might be a space viking type campaign, exploring, conquering, colonising and plundering worlds, something more like a traditional 3I campaign with a bunch of adventurers freebooting around the place.
- Reaver wars - Around Milieu 0. Conflict between the Sylean Federation/Third Imperium and the Reaver states. This might be good for Trillion Credit Squadron type games.