OK, some progress!
Sanctuary
I built up my military fleet and with a bit of fiddling managed to free the Sanctuary system! That's a ringworld protected by old-but-powerful defence platforms about 50k fleet power. It took two goes, plus some worry by ally would accidentally gazump it afterwards, but all looks good.
It had four segments, in each a primitive civilisation had evolved since it was originally set up. Floating lava lamp fungus creatures! Dignified frogs! Robed crustaceans with heads that look like a topology experiment. I set up observation posts, and decided to try to enlighten the second-most progressed species (they were mostly egalitarian, in the industrial age, in contrast to the militarist or authoritarian tendencies in the machine age civilisation). The xenophiles were lovely but there were only two of them and they were still in the iron age.
It's a while before I can get the benefit for four max-size gaia worlds (which is what the ringworld provides) but once they achieve space flight I can presumably eventually integrate their civilisation into mine if I want to.
I got a realistic sense of how slow battleships are compared to corvettes, and realised that I needed to build up heavy fleets at appropriate point and not try to move them too much, but could build more rapid fleets to deal with particular problems.
Centiplizards
Then I rebuilt my military as much as I could. I maxed out my starbases with a mix of anchorages (increasing fleet cap) and energy-production. And got up to about 100k fleet power without going into debt. So I can push it further as I need.
Then as soon as the truce expired I rolled into the second hostile empire and wrapped them all up. It went a lot smoother this time. I had enough fleets I was able to conquer everything without needing to worry about any being outmatched. And enough armies I could conquer all their worlds sequentially.
I lost a couple of ships and armies due to minor mistakes, not noticing one of their fleets reappeared after defeat, or an army driving through a system which had not got conquered yet and getting attacked by the starbase, but I had enough that didn't stop the rest of the conquest.
Then when I'd conquered every planet and every system I was nearly at 100% war exhaustion but it didn't feel like I was struggling against the clock as much. Having been here before I didn't bother to hold out for capitulation, just as soon as I controlled everywhere, I hit "accept" on a status quo peace.
That gave me as a vassal essentially their entire empire. Except they kept their homeworld (because though I conquered it, their government didn't surrender). They kept one system that I didn't quite reach with my "split up the corvettes, conquer all the dead ends" mop up. And (I think?) they kept the toxic world, because it doesn't count as conquered (as I haven't conquered the planet) but I can't conquer the planet (because it's a toxic world and I can't land on it).
That gives me another giant chunk of map and brings me quite close to winning via planets or via federation planets.
Also
Now I keep hitting mineral storage cap. Which is good. But I need to divert some production to energy instead, if I build my fleet further, especially if I incur upkeep penalties for going over fleet cap, I'll need it. I upgraded everything I could and stashed some resources in sectors as I'll need to recover those later if I need resources in a hurry.
I finally got the rest of terraforming! I can terraform barren worlds (well, some of them), and immediately set about doing so. And I don't know if it's actually worth it (most of my planets have very high habitability anyway). And that unlocks the ascension perk I was saving, which lets me start terraforming several of my largest worlds to gaia worlds.
I integrated the previous hostile empire into mine directly, not as a vassal. I mostly just wanted to, I wasn't sure of the pros and cons. I have a variety of perks from various sources which give me bonuses to having vassals, and also to having federation allies, so I wasn't sure what's actually most efficient. I think their population already contributed to my fleet cap (not sure if fully?), plus they already had their own fleets and starbases. But they were probably not very useful. Integrating means they can upgrade all their old-fashioned second-level power plants into level-four power plants, and everyone can migrate freely, etc.
When the process completed, I suddenly had a different number of a lot of important things and I'm not quite sure what was due to what. I downgraded their starbases which didn't seem useful, and disbanded some small fleets which weren't that helpful. And put all their planets in a sector.
What other relevant techs did I get? Gene warriors, super pumped bio-engineered armies. That helped my previously rather wishy-washy armies. I seem to have got a lot more *interesting* biological tech, which is quite exciting, even though my physics and engineering are proceeding apace, but producing a lot of military stuff.
I got a lot of strategic resources, but some of them not permanently, only because I took over a system with them in the war -- I need to conquer whoever controls that system, then integrate them, before I actually *have* the resources. And I need to double check if it matters when the resources are in sectors.
I researched a galactic stock exchange which gave me +10% energy everywhere, which still didn't make my energy income *that* generous. A little while back I made an effort to build minerals not energy, I think I'm supposed to be more mineral poor at this point (although much less constrained than early game). Which will hopefully take care of itself if I build more power plants on new worlds, instead of building mainly minerals.
Relations with neighbours
The final hostile empire conquered *back* the bit I carved off them, temporarily making them sufficiently equivalent to me to be my rival. I'd hoped that in my war, as they entered to defend the empire I was fighting, I could then sneak in and re-liberate some of their liberated bit, but I wasn't fast enough.
But it doesn't really matter, as soon as the war ended, I had a border with them again, and they are now weaker than me, so they stopped being a valid rival, but I can demand their vassalisation and roll up the total territory almost as easily.
And the nearer fallen empire is counted as "equivalent" to me. Their tech is still significantly better, but I'm matching and exceeding them in fleet cap and fleet strength. The other is still a bit stronger, but I'll catch up soon.
When I joined the federation, the other empires were stronger than me, and I got a lot of benefit from having the federation fleet. Now I'm by far the strongest, and I'm not sure how much benefit I get -- I think the federation fleet does provide more military strength than I'd have without it (and with no upkeep), even though only when I'm president. But if I perform the most significant military operations when I'm president, I'll get a big boost.
Now I'm into the third century, an end-game crisis could happen any time, though I don't know when it's most likely to happen. I think I'm fairly likely to unite the whole galaxy before then.
Sanctuary
I built up my military fleet and with a bit of fiddling managed to free the Sanctuary system! That's a ringworld protected by old-but-powerful defence platforms about 50k fleet power. It took two goes, plus some worry by ally would accidentally gazump it afterwards, but all looks good.
It had four segments, in each a primitive civilisation had evolved since it was originally set up. Floating lava lamp fungus creatures! Dignified frogs! Robed crustaceans with heads that look like a topology experiment. I set up observation posts, and decided to try to enlighten the second-most progressed species (they were mostly egalitarian, in the industrial age, in contrast to the militarist or authoritarian tendencies in the machine age civilisation). The xenophiles were lovely but there were only two of them and they were still in the iron age.
It's a while before I can get the benefit for four max-size gaia worlds (which is what the ringworld provides) but once they achieve space flight I can presumably eventually integrate their civilisation into mine if I want to.
I got a realistic sense of how slow battleships are compared to corvettes, and realised that I needed to build up heavy fleets at appropriate point and not try to move them too much, but could build more rapid fleets to deal with particular problems.
Centiplizards
Then I rebuilt my military as much as I could. I maxed out my starbases with a mix of anchorages (increasing fleet cap) and energy-production. And got up to about 100k fleet power without going into debt. So I can push it further as I need.
Then as soon as the truce expired I rolled into the second hostile empire and wrapped them all up. It went a lot smoother this time. I had enough fleets I was able to conquer everything without needing to worry about any being outmatched. And enough armies I could conquer all their worlds sequentially.
I lost a couple of ships and armies due to minor mistakes, not noticing one of their fleets reappeared after defeat, or an army driving through a system which had not got conquered yet and getting attacked by the starbase, but I had enough that didn't stop the rest of the conquest.
Then when I'd conquered every planet and every system I was nearly at 100% war exhaustion but it didn't feel like I was struggling against the clock as much. Having been here before I didn't bother to hold out for capitulation, just as soon as I controlled everywhere, I hit "accept" on a status quo peace.
That gave me as a vassal essentially their entire empire. Except they kept their homeworld (because though I conquered it, their government didn't surrender). They kept one system that I didn't quite reach with my "split up the corvettes, conquer all the dead ends" mop up. And (I think?) they kept the toxic world, because it doesn't count as conquered (as I haven't conquered the planet) but I can't conquer the planet (because it's a toxic world and I can't land on it).
That gives me another giant chunk of map and brings me quite close to winning via planets or via federation planets.
Also
Now I keep hitting mineral storage cap. Which is good. But I need to divert some production to energy instead, if I build my fleet further, especially if I incur upkeep penalties for going over fleet cap, I'll need it. I upgraded everything I could and stashed some resources in sectors as I'll need to recover those later if I need resources in a hurry.
I finally got the rest of terraforming! I can terraform barren worlds (well, some of them), and immediately set about doing so. And I don't know if it's actually worth it (most of my planets have very high habitability anyway). And that unlocks the ascension perk I was saving, which lets me start terraforming several of my largest worlds to gaia worlds.
I integrated the previous hostile empire into mine directly, not as a vassal. I mostly just wanted to, I wasn't sure of the pros and cons. I have a variety of perks from various sources which give me bonuses to having vassals, and also to having federation allies, so I wasn't sure what's actually most efficient. I think their population already contributed to my fleet cap (not sure if fully?), plus they already had their own fleets and starbases. But they were probably not very useful. Integrating means they can upgrade all their old-fashioned second-level power plants into level-four power plants, and everyone can migrate freely, etc.
When the process completed, I suddenly had a different number of a lot of important things and I'm not quite sure what was due to what. I downgraded their starbases which didn't seem useful, and disbanded some small fleets which weren't that helpful. And put all their planets in a sector.
What other relevant techs did I get? Gene warriors, super pumped bio-engineered armies. That helped my previously rather wishy-washy armies. I seem to have got a lot more *interesting* biological tech, which is quite exciting, even though my physics and engineering are proceeding apace, but producing a lot of military stuff.
I got a lot of strategic resources, but some of them not permanently, only because I took over a system with them in the war -- I need to conquer whoever controls that system, then integrate them, before I actually *have* the resources. And I need to double check if it matters when the resources are in sectors.
I researched a galactic stock exchange which gave me +10% energy everywhere, which still didn't make my energy income *that* generous. A little while back I made an effort to build minerals not energy, I think I'm supposed to be more mineral poor at this point (although much less constrained than early game). Which will hopefully take care of itself if I build more power plants on new worlds, instead of building mainly minerals.
Relations with neighbours
The final hostile empire conquered *back* the bit I carved off them, temporarily making them sufficiently equivalent to me to be my rival. I'd hoped that in my war, as they entered to defend the empire I was fighting, I could then sneak in and re-liberate some of their liberated bit, but I wasn't fast enough.
But it doesn't really matter, as soon as the war ended, I had a border with them again, and they are now weaker than me, so they stopped being a valid rival, but I can demand their vassalisation and roll up the total territory almost as easily.
And the nearer fallen empire is counted as "equivalent" to me. Their tech is still significantly better, but I'm matching and exceeding them in fleet cap and fleet strength. The other is still a bit stronger, but I'll catch up soon.
When I joined the federation, the other empires were stronger than me, and I got a lot of benefit from having the federation fleet. Now I'm by far the strongest, and I'm not sure how much benefit I get -- I think the federation fleet does provide more military strength than I'd have without it (and with no upkeep), even though only when I'm president. But if I perform the most significant military operations when I'm president, I'll get a big boost.
Now I'm into the third century, an end-game crisis could happen any time, though I don't know when it's most likely to happen. I think I'm fairly likely to unite the whole galaxy before then.