I was thinking about VBAM scenarios in the shower, and came across a promising variant of the MoO Scenario that I mentioned previously.
Consider a future-feudal empire, whose emperor holds power over the Noble Houses through his extensive spy network, the strength of his Praetorian Guard, and his sole possession of weapons of mass destruction. The Houses pay him tribute in taxes and troop levies for the suppression of rebellions, though they are constrained by imperial law to build only certain technically-inferior ships for the purposes of policing their territories. Though they politick and plot against each other, the ambitions of the Houses are largely checked by imperial power, and peace is had in human space. A dynasty of five hundred years rolls on in this fashion, with technology largely stagnant, until suddenly and unexpectedly the emperor and his heirs are assassinated and their genetic backups destroyed in an act of exceptionally coordinated sabotage. Elements of the Praetorian Guard are implicated, and they fragment as an organization, though the Houses pay dearly to acquire their soldiers and advanced equipment for their own militaries. With the check of imperial power gone, minor feuds over traditionally-contested territories erupt into open warfare among the Houses, often justified with accusations of involvement in the death of the emperor, and long-forgotten weapons development programs and military academies reopen their doors across human space. Each House also seeks to legitimize its own claim to the throne, by means fair or foul; through backing from the Praetorian remnants, through popular support from the citizenry, or through simple ability to take and hold the Throneworld against all comers.
In short - Game of Thrones meets Legend of the Five Rings meets elements of the BattleTech and Traveller universes. In spaaaace.