I'm working on a setting revolving around mech piloting samurai space cats (think Khajiit from the Elder Scrolls or Aslan from Traveller, I promise that I'm not a furry lmao ; ) ). They'll be raiding/fighting the other samurai space cats, a far flung human polity ruled by hypercorporations, space kraken, and newly awakened invasive AI a la Stellaris. I'd also like a little bit of space fantasy type stuff, mostly just importations from other OSR games. To portray this setting, I'm going to use Stars Without Number Revised, along with stuff imported from other OSR games, especially ACK. I'll be using this post not only to present the finished work, but also to organize my thoughts and gather suggestions.
Firstly, I'm going to assume that one credit from SWN is equal to one gp in ACK.
Most personal equipment is in the tens or low hundreds, with the really good stuff and civilian vehicles being in the tens of thousands. Spaceships and military vehicles are generally in the hundreds of thousands, millions, and tens of millions.
Higher TL domains are more productive.
I'd like to keep the current Domain rules for less advanced civilizations TL 2 and below (maybe with some homerules and a little tinkering for different planets and population densities).
I see this species as honorable warrior raider types, like Klingons from Star Trek or Mandalorians from Star Wars, so I'm also going to import ACK's old school experience rules. If you want to level, you have to kill enemies and loot their shit. Experience can also come from trading and ruling a domain, but since the latter will generate a lot more income with access to better technology there'll have to be have to be an adjustment to prevent them from being XP mines. I'm thinking about multiplying the XP threshold for XP from Domains by however much more higher TL domains produce. Similarly, high TL objects like vehicles or spaceships may also have to have their contribution towards XP adjusted.
Domains havea maximum land area calculated from from what I'm terming as the Communications Infrastructure of that domain. The CI is a "fund" in which you invest gp, much like Urban Infrastructure. The idea is that you can grow your domain to encompass the whole planet, but you have to pay for it. CI can be reduced by bombardment, like in the artllery rules from ACK.
TL3 and above Urban Domains take up land. Investment in Urban Infrastructure increases the population cap and reduces land taken up per urban family. Developing higher TL urban domains is a lot more expensive.
Ships and spacestations can contribute to both Stronghold gp and Communications Infrastructure as long as they can effectively be used to protect the planet, attack the planet, and facilitate communications and travel.
Maintenance of vehicles, spaships, and space stations count as gp spent on defence for domain morale purposes as long as they are being used as above.
I'm considering using the rules from Engines of Babylon at least for spaceships' propulsion systems. It takes months to travel to the rim of a solar system, but only days or weeks to travel interstellar. There are both Long Range and Short Range weapons systems, in addition to Planetary Bombardment Range.
Modern day missile and electronic warfare systems, maybe using a version of the artillery duel rules from Guns of War.
Planets are much more isolated from each other than even the most backwards fief. Many lack particular strategic resources needed to power or manufacture certain items. Feudalism, with attendant petty principalities, monopolies, tariffs, etc, flourishes in such an environment. I'm thinking about developing more limits on purchasing very expensive / military items based on the planets' economies. More on this later.