Dan Roseberry and I goofed around with the idea of a 'bisected' or 'rift' Imperium a couple of years back after discussing the old ADV:2 Library data entry. Dan sent me a scan of a hand drawn map and I countered with a MSPaint bitmap. Both are on a virus damaged hard drive that I don't know if I can ever repair.
What we didn't do is shrink the size of the Imperium into the 'proto' size here. That bit makes it all work.
My map had Sylea/Capital in a mid-rift cluster of ~6 worlds. Sylea/Capital was the 800lb gorilla of the cluster. (most worlds were airless rocks or planetoid belts with the exception of a Eden-type, high nobles only, pleasure estate world.) The Rift was wider than the 'Claw' and ran pretty much straight core-to-rim. The Sylea/Capital cluster was linked by a jump4 chain to either side.
Imperial territory on either side was in a rough hemisphere centered on the jump4 chain. The open frontier was to trailing(!), a roughly 2 sector wide strip between Hiver/Rim and K'Kree/Core space.
Spinward was the 'old' half of the Imperium. All the other players were there in there usual positions. Imperial territory there was ~2.5 sectors 'tall' at its widest (core-to-rim, with a full center sector and 3/4 of a sector past that 'above and below'). It was ~4 sectors 'wide' (spin-to-trail, with 3 full sectors running centrally from the the Rift to the Marches). The distance between Vland and Sol was ~1.75 sectors.
If you imagine the Spinward 'Hemisphere' or 'Cone' as a clock, the Vargr/Julians were between 10 and 12, the Sollies between 6 and 7, the Aslan at 8, and the Marches at 9 with the Zhos, Swordies, and Darrians all in contact there. A small rift like the OTU's Windhorn kept the Aslan away from the Marches in great numbers.
This map required some tweaks to OTU history. Everything up through the IW was normal; Yaskodray, the Ziru Sirka, the Confederation, etc. During the 2nd Imperium, the jump4 route was explored with the Capital/Sylea cluster and the trailing territories first settled. (The ZS with jump2 drives did risk it and a few Vilani colonies were set up like the OTU's Vanejen, but nothing major.)
The Long Night was different. The spinward 'half' of the 2nd Imperium fell while the smaller trailing portion 'kept the flame'. The scattered trailing colonies eventually 'grew up' enough to jell into a real imperium and fill all the territory between them. They then recontacted Capital/Sylea and began reintegrating the old imperial spinward territories beyond. Friction between 'vibrant' trailing and 'decadent' spinward began. Cleon came to prominence as the man who brokered an understanding between the two and the 3rd Imperium was founded to put the trailing claims of there still being a 2nd Imperium to rest.
With the impetus from trailing, spinward bounced back quickly, the 3rd Imperium expanded, fought the Pacification Campaigns, lost the Julian War, etc. Spinward moved into the Marches looking for a frontier like Trailing had and bumped into the Zhos, Swordies, and Darrians. The Frontier Wars resulted, Olav killed Jaqueline because he felt the Imperium wasn't supporting the Spinward wars enough, the Civil War kicked off, and Arbellatra - with Trailing support! - put an end to it.
The Imperium is 'bisected' geographically and politically. Spinward has been the most populated, most advanced (focus on continually settling their open frontier kept Trailing's tech progress slow), most wealthy but Trailing, especially the sectors closest to the jump4 route, is now approaching Spinward's 'heft'.
The Alkhalikoi's keep power with unwavering Trailing support and spotty Spinward support. Only the constant threat in the Marches (which is little more than a war ravaged, poorly colonized, armed camp), Vargr border, and Rim keeps Spinward in the Imperium. After losing a frontier to spinward, Spinward tried to muscle in on the operation of the Sollie Autonomous Region and kicked off the Rim War. The result for Spinward was another lost frontier and another enemy on their border!
The Imperium is trying to keep the lid on by sponsoring Spinward colonies in the Trailing Hemisphere. However, shipping megatons of low berths across the Rift is expensive and all the good real estate within more than a sectorof the jump4 route has been taken.
I left it at that. Trailing growing outward and growing tired of Spinward's shenanigans, Spinward hemmed in and hopping mad, and the Alkhalikoi trying to keep the lid on.
Have fun,
Bill
Go with a 'chaotic neutral' Imperium. It's as good/evil, weak/strong, up/down, 1/0 as the man on the spot. As I've put it on the TML before; The Imperium is as good as it wants, as evil as it needs, as weak as it can get away with, and as strong as it must. Think 'realpolitik'.
