Due to lack of time, I was unable to finish this game, and unfortunately also unable to write a detailed report.
This is really a shame, as it was a great scenario and I had a real blast playing it, and it would have really
deserved a better report!
Instead, I can only offer you some hastily cropped and commented screenshots, plus a rough overview how I played the game.
I took the 4000BC start, and thought very long about where to settle. I wanted to settle on the gold hill for several
reasons: Better defense, extra hammer in the beginning, and a connected happiness resource the barbs wouldn't be able
to pillage. But by doing so, I would lose 6 commerce in the long run due to not being able to mine that hill! I had
absolutely no experience with Deity though, and after reading Sirian's warning about the barbarians, I decided to
settle on the hill after all. It turned out later that Sirian had done the same in his start with help.
I produced a second warrior and pulled back the first one after some exploration. Popping a hut had given me Hunting (which I was researching anyway), and I went for Archery next, then Agriculture-Animal Husbandry for the pigs. Huge waves of barbs started to attack Rome, and my first warrior got the combat I/shock promotion, the other combat I/medic, and they managed to hold the city until my first archers were built. Those got not the city garrison promotions, but guerilla I+II instead: Since the city was on the hill, it made no difference, and when one had gathered 10xp, I would move him out onto a hill and fortify him there. This way, my other archers in the city could gather promotions as well, and I was able to produce a worker and improve the hill tiles.
Here's a shot from the fightings while I produced my first settler:
After improving the hills, my worker bravely darted away from the archers and started to improve tiles that were not
directly threatened by a barb each turn, taking advantage of the fact the barbs cannot pillage half-build
improvements. My second city went southwest on the hill at the coast, my next cities east at the copper, south, then
northwest and north of Rome so that Rome no longer was a front-line city and I could construct cottages on the
floodplains. Unfortunately, a barb city popped up southeast at the silver, and it took until 1100AD before I could
capture it and secure the south completely. Actually, I had a short cultrual struggle over the furs with that
barb city. Imagine that - a culture war with a barbarian city!
In 860AD, I assembled a scouting party: Two praetorians, a medic warrior, and a scout to pop any unguarded huts with. In 1010AD, the first barbarian horsemen appeared, and I had to quickly whip some spears to defend against them, especially as they tended to ignore cities and tried to pillage my backlines instead.
While beelining for Civil Service, I got very lucky as Gandhi found me in 1172AD!
Not only could I know better decide what to research next, he also lacked Code of Laws!
It paid off that I had put a scout into my scouting party. 
The barbs had longbows and macemen in 1358AD, which I had not. Fighting barbs with a tech edge was fun...I produced crossbowmen as a counter for the maces, but they lost a lot more than they should. Bad luck, I suppose. But Gandhi seemed to sense my problems, and helped me by gifting me Feudalism, for longbows! Wow, thanks!
Qin found me in 1364AD, and once again it paid off that I have a pretty good idea what techs the AIs prioritize and which they tend to ignore.
I also didn't know that the barbs can make stacks, too! That put a frontline city of mine into great danger, but it survived - barely.
An even greater stack appeared at my northwestern front, at a city I had believed to have protected more than enough. Guess I was wrong...
Ouch, losing that city along with its units (2 longbows, 2 praets and a spear I think) threw me back some. But at least I was still in the trading loop!
Later, the AIs founded cities on my borders too, and begun to capture barb cities themselves. I raced for some.
While I brought macemen and crossbows, look what Gandhi brought to the fight...
But while Gandhi and Qin finally had run away tech-wise, at least
I had managed to keep Isabella and Louis happy. They couldn't threaten me, but I had caved in to their demands
anyway, to be able to trade with them. Careful research and some 2-fers helped me to slowly catch up.
The barbs had riflemen next, before I had grenadiers, which again caused me some headache. But the AIs were helping me now more and more.
In 1869AD, I discovered Computers and went for Fission next. The barbs were no longer on the continent, which had been fully settled by now, mainly by Gandhi. Relations were very good, in fact I would have been able to sign a defensive pact with either Gandhi or Qin! I had started to produce bombers and a navy already before I ran out of time to finish the game. Here's my empire at the end:
I'm sure I could have won this. I only needed to remain at peace for another 50 turns or so. Then, I would have had enough fighters, bombers and ships to stave off any attack that might have come, and then would have been able to attack first Qin, then Gandhi. With enough bombers and later applying the "Sirian Doctrine" (bombing coastal cities with fighters from carriers and battleships, then amphibiously raze them with modern armor), you can overcome the Deity production advantage (they no longer had a tech advantage!). I had also planned to shut down research once I would have had access to stealth bombers and modern armor, and would have used the money to bribe Gandhi to help me against Qin.
This end-game, modern warfare would have been very time-consuming though, and I think if I would have had the time, I had only razed some city to prove it's possible, then retired the game because of the tedium involved.
Again, sorry for that mini-report, and a huge thanks to Sirian for a really good scenario! I enjoyed the fight
against the barbarians very much. 