Well, I knew Immortal level was beyond my ability when I started this game...
After 1 AD, I completed the Colossus, to try to extend my financial/tech lead. I tried building a couple other wonders, but kept getting beaten to them by the AI. I did get the Mausoleum, which extended my golden ages, including one from building the Taj Mahal.
In 1170, I tried to use my tech advantage to attack Shaka in the hub. Not only did he have huge stacks of his own units in reserve, but DeGaulle immediately joined the war against me. I managed to take one city from Shaka, before signing a ceasefire with him. Then I had to reject a number of AP motions to hand back that city, which played havoc with my city happiness.
I managed to conquer two hub cites from DeGaulle (with two of Shaka's cities still in between that territory and my own), before making peace in 1560.
Gandhi, meanwhile, continued to be everyone's target. I even had to join the fight when I didn't want to oppose one more AP vote. I didn't actively participate in the war, though. Shaka forced Gandhi to capitulate in 1670.
I founded Sid's Sushi in 1810 and tried to use the culture it produced to expand my borders in the hub. It only had a marginal impact, though, and cost me a lot of gold. Meanwhile, first Monty and then Shaka attacked DeGaulle, each conquering one city and then leaving huge stacks to garrison those cities that were surrounded by French territory.
I was hoping to win a space race, but with the AI advantage, Monty and Shaka finished Apollo first. And just before I finished my Apollo project, Shaka/Gandhi attacked me in 1892. I was able to hold them off, and even capture one of Shaka's hub cities, until Gandhi broke free from Shaka and made peace with me in 1906.
Monty attacked Gandhi again, forcing his capitulation in 1917. Shaka, who continued to refuse to talk to me, inexplicably voted in favor of an AP motion to end our war--as if I wasn't eager to end it at the earliest convenience!
Usually, at this stage of the game, all of the AI settle down for a peaceful space race, which Monty was on track to win. Not in this game, though! Monty/Gandhi attacked DeGaulle in 1938, with a blitz of modern armor and other advanced units. And Shaka attacked me again in 1946, with a blitz of his own units that finally had a open path from the French city he had taken. He quickly took two of my hub cities.
Monty had become Secretary General of the UN, and I missed a chance to end the game with honor by voting for his diplomatic victory. Instead, I reflexively voted for myself before realizing that was pointless. Rather than trying to drag out the game until another UN vote, I retired from the game in 1950.
Oh, and did I mention how AI spies were constantly poisoning my water supplies, destroying my improvements, and occasionally stealing tech? Fun, it was not.