Well, I took the Challenger save and did a Quechua rush.
Julius is dead.
Isabella was reduced to 1 Holy City while the Barbs now own her other Holy City.
Cyrus was reduced to 1 City.
The Barbs even captured and razed my capital for me once most of the Forests had been chopped and after expenses were getting quite large for having captured other Cities.
Rome is my new capital.

Everything was going really well...
Then, I got greedy. I went after Genghis when I saw a Worker improving his Horse. "I must not let him get Keshiks," I thought. Since I was also pushing a Strike, I just blatantly threw away units at him, even though they weren't going to win (insufficient Quechuas and Axemen against Archers defending a Wall-protected Hill-placed City). Well, it was a mistake, as he showed up with Swordsmen and Axemen in short order.
As of 1 AD, Genghis has "expanded" all of the map by capturing Cyrus' ex-Cities that had been Barb-owned Cities which I had been saving for myself. Of course, Genghis also got his Horses hooked up. He has captured one of my 4 main Cities and is about to capture another one of them.
Tech level, having starting with no techs, is only has high as Writing and Bronze Working, with me just having picked up Hunting so that I can finally hook up my first Happiness Resource (Fur).
Lacking Pottery and keeping too many Cities for a long period of time (keeping them long enough for the Barbs to capture them, for me to recapture later) kept my economy on ice for too many years. Missing the 2 starting techs due to taking the Challenger save made it just that much more difficult to get to Pottery in time and I ran out of funds before I could make it there, taking probably close to 2000 years to research that tech.
I will fight it out and will use every trick in the book, but I basically handed away my whole advantage and plan to Genghis by getting into a war with him when I wasn't prepared for it. By doing so, he was induced into building an army which just marched all over the Barb Cities that I'd been saving for myself. With him having more than twice as many Cities as me, a Score that is three times that of mine, and armies at my Cities' gates, it will be only by my Civ's sheer force of will that we will stand a chance to live on.
Since I haven't met any other AIs, I must conclude that the others, which all lead the tech Leaderboard, are all on some big happy continent somewhere as Buddhists (since Isabella is one-City-hogging Hinduism while the Barbs are one-City-hogging Judaism). It'll play out more like a Deity game, I figure, if I manage to survive... AIs on another continent (unless there is a land-bridge that I have yet to find) building all of the Wonders, getting far ahead in tech, definitely getting Circumnavigation (probably before I even learn Alphabet), then settling my lands before I get a chance to take my saved Barb Cities back from Genghis.
Meanwhile, I will be whipping my remaining few Cities to Size 1 for many years to come, just to build sufficient units to stay alive.
My planned Victory condition? How about staying alive until the end of the game.
One positive bonus: no Praetorians.

I've had to deal enough of those recently, thank you very much.