One expansion limiter I liked was in Distant Worlds. You could only expand as fast as you could build fuel sources in further out locations, unless you enjoyed wrestling with the auto-refuel AI. But then, wouldn't work in this game due to a complete lack of fuel systems.
oh, something like it could work, just not called "fuel." in fact i think the game would be immeasurably better if they:
1. remove construction ships, science ships, and colony ships from the game.
2. level 1 starbases can send "Expeditions" to other star systems. Initially this is just neighboring systems, with longer distance expeditions unlocked through tech.
3. There are four types of Expeditions:
- Exploration Expeditions survey the system (takes time, of course) and identify resources and anomalies. They have to be completed before other expedition types. On completion, they construct a navigational beacon in-system. The beacon allows the other kinds of expeditions.
- Mining expeditions claim the system and upgrade the navigational beacon to an outpost, and begun constructing mining stations in all known. Requires a special starbase building.
- Science expeditions don't claim the system, but investigate anomalies and complete special projects. Requires a special starbase building.
- Colonization expeditions colonize planets. Requires a special starbase building, but you can just pick any pop in your empire as the original pop.
4. make a bunch of necessary balance and infrastructure changes, like increasing starbase building slots dramatically and making your initial starbase start with all the buildings listed above. pacing of the game would probably change dramatically which would require any number of changes, etc.
if they were really ambitious, the above would result in all kinds of automated NPC ships flying around and simulated resource tracking, like the non-FTL mining ships dropping ore off at the in-system outpost, which processes it into Minerals, and then FTL cargo ships automatically ship the ore to the nearest planet/starbase/whatever, which is then building ships/buildings/whatever per your orders based on resources actually received. and then pirates are actually trying to attack those instead of spawning in random empty systems you never bothered to claim because you didn't want a 1% hit to unity
anyways