Consolidation and Learning Replaceable Parts
After making peace with Zululand and demobilizing, in 1255AD, I began a period of growth and consolidation. I was still involved in a number of wars but they were not intense.
In 1265AD I finished driving America off my land. I declared war on the Mongols and drove them off too, razing two cities:
The Inca had a few cities in my area and I wanted them

I also wanted to slow the Inca development, they were becoming too strong. But I would not be ready to invade the Inca homeland for some time. I wanted to remain focused on consolidating the homeland for score. So in 1275AD I bought an MPP from China, traded Aztecs Communism for an MPP and a luxury, then told the Inca to leave my lands. They declared war resulting in a nice happiness boost.
I paid the Zulu for an alliance against Inca. I hoped that someone would eliminate the Zulu - they were ahead in tech and I wanted to remove the possibility of those techs being traded around.
I destroyed the Inca troops wandering through my lands. Since China had MPP with Inca as well as with me I didn't attack the Inca cities. Instead I surrounded them and ended my turn. I had enough armies to handle that, an amusing sight:
The Inca bombarded my coast so the Aztecs and China lept to my defense, declaring war on Inca. And the same happened with America (I hadn't been able to make peace yet) - she bombarded my coast and Aztecs and China declared war on her. Next turn I immediately took the Inca cities in my area of course.
In 1280AD the Zulu attacked China and because of my MPP with China I was at war with Zulu again, breaking my peace agreement with her. Oh well, it wasn't intentional on my part.
In 1290AD my solitary scientist learned Electricity. I began serious research at last. I wanted Replaceable Parts! Researching it was expected to take 14 turns, ouch.
I sent a small invasion force to visit the last remaining Zulu town, on an island just off my coast. I took the town but the Zulu remained in the game, they have a settler somewhere.
At 1330AD I'd filled in settlements and spread my borders to be just 60 tiles from Domination. I'm still managing all workers manually and turns are now taking a very long time. (And real life keeps trying to interrupt

) But the end of improving the land is in sight now.
In 1340AD I learned Replaceable Parts. I'd improved my research rate a bit by building libraries and universities and by assigning scientists in towns which had reached their growth limit.
I've immediately reassigned many citizens to be Civil Engineers. They'll help with the task of building aqueducts, marketplaces, and harbors in corrupt regions.
Learning Replaceable Parts had been a high priority because it enabled Civil Engineers. The next steps are not as clear, this is a major decision point.
Should I switch to Republic now? Finally this seems a viable option. I don't have urgent war priorities for a while - I need transports before I can mount any large scale invasion against a rival. By the time anarchy ends I could make peace with America and Zulu to avoid war weariness. There are a lot of factors affecting this decision:
o Republic would allow faster research, something I'd really like at this point. And slightly lower corruption would of course be welcome.
o I'm in a constant cash crunch. There are lots of things I want to rush but not much gold. No gold at all if I research at 70% and use 20% to maintain a good level of happiness.
o Getting ahead in tech will probably not help the cash crunch problem - for some reason my rivals have had little excess gpt so far.
o I can probably only gain spending capacity in Republic if I disband some of my forces. At this date I have 554 units. 243 of them are workers and if necessary can be joined to cities, leaving slaves to handle remaining improvements. 18 are obsolete military units which could be disbanded in Republic. But the rest are current units and their numbers will have to grow in future.
o In a while war weariness will again become an issue in Republic. I think that controlling the Inca, Aztecs, and perhaps even China will require long expensive wars, quickly reaching maximum war weariness.
o Rushing improvements in corrupt cities will largely be handled by Civil Engineers. Gold will not be as important for this part of the game as it was pre-Conquests.
o The worst case anarchy time is nine turns. During anarchy I'd lose some population (a bit of starvation plus some missed growth opportunity), I'd lose research time (unless I used scientists at the expense of lost growth) and I'd lose construction time.
I've decided I won't make the switch. I think I can reach my next major goal (Transports!) at least as quickly in Monarchy. The costs of switching seem likely to outweigh the gain at this time.
Having made that decision for the current situation I expect I'll stay in Monarchy for the rest of the game. When I reach the next point where it would make sense to reopen the question I don't expect it will matter anymore. Milking builds (aqueducts, marketplaces, harbors) should be done or nearly done by then. So I might as well stay in Monarchy till the end and use MPs to help happiness in a few places.
I'd hoped to trade Electricity for Medicine by now. But only Zulu and Inca know Medicine. I have nothing to trade Zulu and I wouldn't trade Replaceable Parts to Inca even if we were at peace. So I'm starting research of Medicine, heading for Scientific Method. Better that I learn those two techs and then get two others for free than that I research two other techs and leave the Theory Of Evolution for an AI to build. I've started a ToE prebuild.
I see just two rubber sources outside my lands! Inca has one of them, America has the other. This presents a good opportunity. I have three Cavalry armies at this point which are small enough to travel by Galleon. I'll send one, with some Infantry and a spare Cavalry to join the army on the other side, to try to reach and control the Incan rubber. I don't have Galleons where I need them for this and don't have gold to rush them, so I've rushed them by disbanding some cannons. If this works, and I get to that rubber before the Inca learn Replaceable Parts (there's little doubt they're currently researching it since they know Electricity), the Inca will be a lot easier to deal with later! There's a good chance that the American rubber supply will remain in America's control - it is on a smallish island which the other Civs are unlikely to invade successfully.
Inca culture is becoming a major concern. It is at 100378 and increasing by about 900 per turn. I'm not sure whether I have enough time to mount my large invasion. If they mobilize I should be ok. And if I can trade with another rival for at least one tech that will help a lot. But it is worrisome. I'd like to spend some gold on luxuries for happiness (and thus for score) at this point but I don't think I dare - I must research quickly.
If I get past the Incan threat I should be ok. The Aztecs are much lower in culture, roughly half the Inca. Zulu are nearly as high as Inca but won't be gaining much more culture
Perhaps I'll start sending individual Cavalry to visit the Inca lands soon and try for promotions. If I can create a bit of a wedge over there then I might start creating new armies at the warfront and making a dent by razing a wonder city or two before my main forces arrive later on.
My next priority after the Inca rubber will be the American rubber if it seems in danger of falling into another Civ's hands (America is too weak to present a threat anymore.) If America seems safe I'll go for luxuries. I have just five of my own. China has the only furs in the world, Aztecs the only silks, and Inca the only dyes. My other two Cavalry armies which can travel should be able to take a luxury or two. Starting with the Inca dyes of course
And I'll continue milking in the homeland of course. Settlers, aqueducts, marketplaces, finish improving the land, etc., while I research toward Combustion. So much to do!