18 Civilizations on a Duel Map

Yes, this is my preferred setup. If you go donut (ocean) then it is even tighter, and every city is on the coast. If the speed is 'epic' then you are sweeping through cities faster than the AI can garrison them.

Capturing cities quickly results in expenses growing intolerable, but the diplomatic advantages of gifting cities to AIs (always on the opposite side of the donut to the gifted city) are well worth it. You end up keeping research at 100% because the loot from city capture pays for all your upkeep. Wonderspamming is actually practical (although no Marble on a donut).

Alphabet ~3000BC, Shrines ~2000BC, diplomatic victory ~ 1000BC is quite doable. My favourite though was a Christian diplomatic victory at the BC/AD crossover.

I surprised that someone resurrected an 8 year old thread.

Never thought about this. Will definetely try this option this weekend!

Was trying it yesterday, I think Monarch difficulty. It's fun but a little on the easy side at the same time. In my game, barely any Ai ever managed a second city (somebody was lucky enough to have a peninsula extent far enough to place a second city but it sucked) and no Ai managed to grab another's capital. I've stomped a bunch of nations already and it's like taking candy from kids.

Ai is not coded to be efficient at what is actually is a OCC for everyone.