I just finished a game on the same settings I've been playing for a while (Byzantium, Huge map, Epic speed, events mod). First game I've played all the way through for some time!
I started slow, and got forward settled a bit. I chose to favour my monopoly and pantheon by expanding south and east, allowing the Songhai to grab the spots north of me. Once I got access to my uniques I steadily made my way up the ranks to compete as a religion, then in tech and policies, and eventually militarily as well. I managed to build some of my favourite wonders (Artemis, Angkor Wat, Machu Picchu, Himeji Castle), but was beaten to others (Forbidden Palace, Sistene Chapel, Porcelain Tower, the Louvre).
The defining moment came when I met the Maya, who I realised had build about half of the wonders in the world and had a strong lead in tech on the rest of us (7 or 8) as well as policies (3 or 4). Aiming to beat them I was able to catch up to within about 5 techs and 1 policy, but meanwhile they just kept on pumping out wonders like there was no tomorrow. Unfortunately soon they took Rationalism and shot ahead in technology again. Soon after they adopted Communism as their ideology and from that point pulled back well into the lead - being at least 9 or 10 techs ahead for the rest of the game. I knew I wouldn't be able to beat them to a science or tourism victory and I was in no position to try for domination this late in the game, but I did gain control of the world congress at that point. Most people seemed to like me or at least prefer me to the other contenders.
Around this time I declared war on Netherlands (four people asked me for joint war declarations against then on the same turn) who were already embroiled with an existing war. That war ended sooner than I had anticipated though, and I found myself faced with the might of their naval fleet coming for my coastal cities. I thought I was done for, but with support from land units and the timely arrival of reinforcements from my farther settlements I was able to turn the tide. I captured two cities (Arnhem and Haarlem) which I razed due to battle damage. At about this point, the Swedish fleet turned up in force and threatened my island cities. Happily they were willing to peace out soon afterwards so I didn't loose any. I quickly resettled the locations the Dutch cities used to occupy, which later turned out to include my only local source of oil!
When that was over, I used the world congress and the Maya's unpopularity to sanction them and implement other policies that would help smaller players catch up (as well as benefit me). I donated at least a dozen techs to the Maya's neighbours, as well as 100s of gold per turn to two of them. And frankly without it I think both Poland and Brazil would have been wiped out by the Maya and their smaller buddies Assyria. However, in spite of all this they continued to dominate, and going into the late-game another rival reared their head: my neighbours Siam - who were going for a diplomatic victory like me and had completed the Statecraft tree to boot (where I had taken Artistry instead).
Siam dominated the political sphere, snagging almost half of the remaining city-states (some had been captured). I fought back but wasn't making much ground, so I proposed to decolonize them and happily other civs supported me! Which was awesome becase now I was in a leading position in city-states. Except that over time, in spite of me completing city-state quests and building diplomats, Siam overtook me influence for many of them (which also put me in a negative position with regards to certain resources). So I decolonised them again. And the same thing happened lol. I deconolonised them again, and both World Ideology and the United Nations subject was proposed but in spite of my support both got voted down.
In the meantime, the Maya had finished the tech tree and was building spaceship parts. I had gained a strategic monopoly on Uranium which was nice, and helped me in my war against the Zulus with the help of Polynesia and Sweden. I knew this might be my last war in this game so I went all-in. I liberated two cities which had belonged to my friends Polynesia and Spain! Siam managed to get a lead on me in science and started building spaceship parts of their own, although not fast enough to catch up the Maya. As I was busy with war and struggling over city-state control, the Maya built their final spaceship part and won the game! Which honestly made sense, I would have been more concerned if the AI had lost from such a strong position.
Something that was odd was the spread of different religions over time. I always tried to convert neutral targets and with Byzantium's strong faith game managed to win two of my neighbours (the Songhai and Sweden) as well as all the nearby city-states, in spite of competition from both Siam and the Netherlands. I never tried to convert founders though, and mostly there were several competing religions on each continent (total 7). In the late-game though, I noticed that none of the third-party cities had been converted to other religions as they often were during the early- and mid-game. So I looked around and to my surprise found that almost every city on my continent had been converted to my religion - including Siam and the Netherlands. And in fact most of the other continent had been converted to Spain's religion. There were effectively only two religions left in the world, apart from a few cities loyal to each of the other factions.
On city defenses: coastal cities were strong, but in most of the wars where I captured or defended cities, whether or not the city had an arsenal or later on military base was more important (AI cities usually did). And several city-states (which are all coastal or on islands with this map type) were captured in spite of their extra defenses. I was fighting with gatling guns, ironclads, and cruisers in the first war- and then with destroyers and battleships in the second. I didn't have much of an issue taking cities once most of the defenders were removed from the equation. On the other hand, in my earlier war against the Songhai (non-coastal cities) I fared well but their numbers kept me at bay long enough that even with minimal losses I didn't make much ground.
Generally speaking I was pretty happy with how the game went. The Maya have been pretty strong in my recent games so I do wonder if they warrant a nerf. They had a very nice starting position though, with room to expand. I had a look at their beliefs and the only things that stood out were Tutelary Gods as a pantheon and Veneration as a follower. Both are strong but not enough to explain such a lead IMO. If not for Spain dominating their continent religiously in the late-game, the Maya probably would have been even stronger. What did surprised me was that while the Maya were unpopular, they weren't universally hated as I would expect a civ with half the world's wonders and a big tech lead to be. Siam, the Netherlands, and I each made enemies of our own despite being well behind on those metrics. I suppose other factors may have come into play.
As I mentioned in the diplo thread, I liked the diplomacy - I had friendships, defensive pacts, denouncements and declarations of war in a way that felt good. Dynamics changed over time in a way that was interesting but not inconsistent. I'm also a big fan of the buffs to lakes and pastures - they are good without being too good, which makes me happy.
One thing that annoyed me a little was how difficult it was to compete with Siam over city-states despite sending diplo units non-stop in the late-game. I guess that's what Statecraft is for, and they had a good reasons to compete with me - both because of their UA and their victory condition. I think the main reason I was still able to control the world congress was religious authority and using my great diplomats for embassies. If I hadn't been able to decolonise them I'm not sure what I would have done as they had a bigger and more advanced army than me at that point.