Researching technology was very slow, as was city growth - but culture and researching new policies was not adjusted to be in-scale with this. By the end of the game I had unlocked almost all policies except for the Ideology policies, which I was held back on by slow technological progress. Growth was also a big issue, and the cities were unable to gain additional population at an at all reasonable rate later on in the game. Western Europe certainly got a nice buff from the grassland improving later on, but the Mediterranean remained rather stagnant. Also, because of the slow technological growth and lots of turns, I was able to get all cities to build (effectively) all buildings, which removes a sense of the opportunity cost of pursuing one route or another in each city, as everything can be constructed in all of the cities.
The ability for city states to shrink to just a single tile in size was a fun and noted feature, especially for crowded Europe. However there was an incident where I had land (including a citadel) directly adjacent to a Pirate stronghold, and when that stronghold was destroyed, all land ownership in the surrounding 6 tiles was nullified, resulting in my land and citadel now becoming unowned. It is noted that Pirate strongholds cannot be captured.
I used the 5-turn plan feature to try and mitigate against collapse, but am still very unclear on how it works, what effects it has, how to impact on the stability of each category, how stability relates to collapse (I did collapse once or twice as Greece!), etc. I also think it would be good if a notification is received at the end of each 5-year plan period - assuming that it does work, it is not clear why the player would not want to use it at every opportunity.
The fact that Diplomacy only works for civs you are currently nearby to in the early-to-mid game is a great touch, but it would be good if there was a notification to let you know when this changes.
I noted a couple of barbarian encampments in central Africa that were directly adjacent to each other and both empty, which was a bit strange. Also I think Africa would generally benefit from having more civs based in it from the middle ages (e.g. Mali, Kongo).
In this playthrough, the Celts were a massive pain for the Romans to deal with, and Rome consequently never really got off the ground as a power. Also, as Greece, having your territory constantly yoinked away to form the Byzantines and then the Ottomans, then whoever is deciding to respawn at any given time, is initially frustrating. But each subsequent respawning, you as the player are stronger, and because the AI always come back as 'at war' with whoever last killed them, and they rarely respawn with any decent units, it becomes trivial in the late-game to recapture cities. But the constant capturing and recapturing does impact on the general growth of the civ. Although looking back at it, it is fun to see just how many different configurations of my little Greek empire happened throughout the game. It is unclear what parameters make a civ spawn or respawn - is it entirely down to certain dates? Or does the stability of existing civs in the area have an effect? Similarly, the dates at which locked wars are instigated by the game, and at which peace occurs - are these entirely linked to dates or are they based on stability or other concepts?
One Germany came into the game, it was obvious they were the biggest threat. They quickly wiped out France and dominated Europe for the 1800s, with their RPV points being the highest of anyone. France did reappear briefly but (much like the late-game reappearances of the Ottomans for me), they were defeated by the Germans again within a few turns. It was a similar story with Spain, although I ended up liberating one city each of theirs from the Germans, so both struggled on as tiny powers throughout most of the game, sandwiched within the German empire. It was clear from Germany's quicker technology in the late game and bigger miltary that I couldn't even try to compete militarily past the early 1900s. It would be nice perhaps to have liberating civs and bringing them back from the dead rewarded somehow in the victory points. Bismark also loves stabbing civs in the back! Always straight from a friendship pact into war or something similar!
Although I still was not aware of how other civ's RPVs were being calculated, so it is difficult to know how to play against them! It was during this late medieval/early industrial era that I realised that the only way Greece could win was by gaining Wonders. I was also by now comparing the RPV scores for Greece against the normal points and was realising which categories were factored to produced the RPV score and by how much - with Wonders retaining their normal score exactly. I think it could be helpful to have a RPV advisor, like the other in-game advisors, who can provide some direction and assistance on achieving your RPV, especially for players using a civ for the first time.
I understand that archaeologists have been removed from the game, but this nerfs wonders like The Louvre and other cultural late game concepts involving artifacts. Would be good to see this rebalanced.
Despite European colonization of the Americas being well underway by 1878, there were no religious cities, except for one Dutch colony in South America. Given the driving force of religion in the narratives of colonization, it would be good to see more effort from the AI to ensure their new colonies are religious. Also I noted that the English cities in the central America retained their Maya names.
When Italy came back as a minor civ in the late game, the Papal States stayed, which massively divided up the territory and made Italy an easy target. It would have been good to see the Papal States reduced to just a tile or a few, rather than retaining their entire city.
Dead civs always remain on the trade options with other civs - I haven't yet figured out how to exploit this by trading to go to war with a civ that's already dead, but presume this could occur if not dealt with!
I also realised that I was no longer able to construct Shrines or Temples in the late game! Is this a feature or a bug - I had not realised that these buildings had an expiry date.