Immortal is still above my play level, so I tried taking it slowly and paying much more attention to the diplomatic side of the game.
The world continued peacefully in the early AD. I completed the Pyramids in 375. In 900, I got the circumnavigation bonus. Isabella, Frederick, Joao and I were all Buddhist, and so on good terms with each other. Isabella, Boudica, and Charley started plotting, and everyone disliked Elizabeth, but nobody started a war. In 1050, I put my berserkers to work and attacked Elizabeth. All the AI who were plotting couldn't be bribed in. I thought they'd join the war on their own accord, but they sat on the sidelines as I took five cities, including all of her mainland. With a handful of islands left, Elizabeth was willing to capitulate, but I thought she'd be more valuable as an independent target of the others' dislike, so I made peace in 1250, in exchange for Guilds.
Boudica would be my next target. She was tougher, so I decided to begin my attack in 1310 by sacking her capital. It cost me 6 of my berserkers, but Bibracte was razed! I thought I could capture her navy in port, but it had moved out a turn before my attack, so I had to destroy it piecemeal on the next turns. She managed to land one ineffectual stack outside York, but that didn't last long. Charlemagne attacked me in 1340, but his inferior navy also went to the bottom.
Isabella had built the AP and been elected its first leader, but Joao and Frederick had supported my bid for the papacy (err, for high lama?) in 1380. I called a vote for war against Charlie in 1480, Isabella supported it, and now all of the Buddhist alliance were at war. In 1500, Boudica capitulates and gives me Economics.
Despite having three strong allies, they don't seem to do anything on the battlefield, while I take four Holy Roman cities and force Charlie to bend the knee and give me Divine Right in 1580. Meanwhile, Isabella's Buddhist population has grown so much that she elects herself back to the AP, over the combined opposition of myself and the other two AP members.
Now I had to decide if I wanted to pursue a peaceful victory with my pleased and friendly neighbors, or if I wanted to do some backstabbing on the road to a military victory. I figured Isabella had too much population for me to win a religious or UN victory, and the AI had enough of a tech advantage to make a space race chancy. So, it was time to betray Isabella. But how to do that without the others joining against me?
Isabella actually helped in that regard. As I started repositioning my navy, Isabella attacked Elizabeth in 1585. Then in 1605 she calls a vote for a holy war, which I eagerly support. Now everyone is at war with Elizabeth and the other AI will be too busy to turn on me.
In 1620, I declare on Isabella. I start by razing two large cities on her mainland and capturing a couple islands, then I start capturing and holding some of her mainland cities, including Madrid (with the AP, Mahabodhi, and three other wonders). She capitulates and give me Corporation in 1665.
In 1685, I attack Frederick. He's made some curious choices in his research. He has Combustion, but he doesn't have oil, so no destroyers. (I've just finished researching Combustion in 1670.) He also has Assembly Line, but he doesn't have Rifling, so no infantry. It's so nice when the AI squander a tech advantage! I capture eight of his cities, including Berlin, before he's willing to capitulate in 1725.
And here's where I throw away a lot of my careful planning and game play, with one click. I want him to give me a tech along with his homage, as I've done with the other AI. So I ask for Assembly Line...and then I make the offer without also selecting the capitulation option.
That gives him ten turns of peace before I can resume my war.
So, in the meantime, I declare against Joao in 1740. I capture seven of his cities, including Lisbon, but he won't capitulate. In the forgotten front of the war, I've gradually been taking Elizabeth's islands (the AI again having accomplished nothing against her) and destroy the English Empire in 1790. Joao still has a lot of defending infantry, with which he might retake some of my prizes, so I sign a ceasefire.
Because...it's time to resume the war with Frederick! I capture one more city and now he capitulates, officially, in 1802.
I go to war with Joao again. Now I have some tanks and fighters to help in my offensive. As I capture more cities and he still refuses to capitulate, I give a couple of my Buddhist cities to Boudica and Charley. Now everyone is a member of the AP and I have enough votes for a Religious victory (with enough in vassal hands that I'm not disqualified by having an absolute majority in my own hands), if Joao remains stubborn. But finally he capitulates and gives me a Conquest victory in 1822, on very turn that the next AP vote would have been called.
I really wish I hadn't misclicked, and it probably cost me a place or two in the standing, but it didn't stop the ultimate victory.
)
I finally get 3x power, and Liz says 'I'm too far away!' to be my vassal. This is new. Wouldn't happen on the maps I usually play. Reading the code, it says I need to be in the same 'area'. I'm pretty sure that means one tile touching or one city on the same landmass and doesn't mean: 8 tiles touching (land target). I have to scramble to get a settler down to her before there are no islands left with room for 2 cities.
I settle my city on a small island with one of her cities and she instantly peace vassals.
But then the Islands map has another nuance. There isn't the usual unclaimed land that other maps have, so I can't get anyone to peace vassal since each one puts me over the land dom limit already. In fact, the only way I could get even one more was to gift 3 cities to Charley to lower my land and then Fred peace vassal'd. 
, which kinda hurt on the production front. And I think I only got one tech (Medicine) in trade from anybody (Boudica) once the Space race got going, even though I got Fred to friendly for awhile. Maybe a hidden modifier so he wasn't really "friendly"?
I guess I should not have let Fred get MM.
