Apparently no one above is making use of the C3C bug. I was playing Rome in a Regent game. I started with discovering the Celt on the first turn, and started trading with everyone except the Carthage (I hoped I could). It's very easy to drag everybody against the poor Carthage, and I traded workers, and... wait! I can trade cities!!! So I got the Asian city of Egypt and the southern most city by the Nile, a city at Northeast coast of Turkey from Persia, and a city by the Black Sea from the Macedon, just by asking all of them declaring war on Carthage, and sometimes given the Math.
I didn't trade ally with Celt, because I was planning to invade Celt soon, and I didn't want other ally withdraw their promises too soon.
I loaded the open game the other day, and found that Egypt has an extra worker popping out for trade. So I bought it. And with suspition, I save/load the game, and got another popping out from Celt. Then I save/load and nothing else. I got 8 workers on the first turn from 4 AIs. I'm not sure if it's another bug or not.
War on Sicily brought me Golden Age and I started building Wonders on the central cities. I waited for Rome to grow to 7, then i add all 5 slave workers except 3 from Celt into Rome to make it 12. I set up 4 cities chasing Wonders. And got most of them.
One of the road wandering unit found Goth, and Scythia came to my Asia Minor city. I made all of them having war with Carthage.
I won major victories against Celt and offer peace with some other Celt cities. Later, Celt built some new cities, including one in England. So nice, another war limited Celt to city at Southern France, and got all other cities by offering peace, yes, including the english one. And now they built another city for me.
)
War with Carthage was a little slowing going because they never talked to me.
( I invaded the capital first after taking the islands. And then wiped out the eastern cities first. By that time, I've got too many legions for Carthage to handle. The allies are eventually withdrew war with Carthage one by one. But they are busy fighting each other. (Or I forgot to mention that I set them to be most aggressive.
) When stupid Egyptian formed Ally with Macedon, I saw dozens of Immortals accrossing my Mideast city. But I kept silent, just pop rushing some new cities to expand. Egypt was almost elimated. But after losing all started cities, they made peace with Persia.
I eliminated Carthage recently and closing to victory limit. Carthage got war elephant later in the war but was outnumbered by my legions. I changed the government. And don't know what to do next. Invade Goth? Peaceful expanding? Fighting with Macedon to practice massive war, and fight with Persian to try an even bigger one? I built 8 cities out of the 4 cities got from the 1st turn which successfully limit the expansion of Macedon and Persian.
None of the 5 civ ever declared war on me, and when massive troops accross my distance cities. I kept silent and watched them fighting each other. My pop was more than 50% for some time. Thinking of how can I win by using greeks. It will be hard.