Score, History Rank: 14063 (normalised), Hammurabi
Winning date: 1490AD
Difficulty: Viceroy
Gamespeed: Normal
Version, subversion: SVN 615, Master Map v0.0
Scenario: 3000BC
Victory: Unique Religious Victory, Orthodoxy
Choice:
As orthodox you have to counter all catholics, so Europe is the obvious option. Moreover, it will be very helpful to control both catholicism and orthodoxy, so Rome is the obvious option. Byzantium can do too, but Rome can give a significant time advantage.
Strategy:
Roman empire, setting the orthodox empire:
I conquered Cathrage, Greece, Egypt, Mesopotamia and Persia as in all games. I built the great lighthouse and the colossus to forge my economy. After that I switched straight to Theology and found catholicism. Then I conquered the rest catholic world (Ethiopia), and built the apostolic palace. This way I managed to found orthodoxy and recieve the Hagia Sophia. Meanwhile, I built all my cities, like forums, courts, libraries, baracks and all sorts of useful buildings. Moreover, I trained and captured many workers, maintaining the biggest empire in classic, middle and renaiscance ages demands plenty of them. I emphasised on orthodox churches and cathedrals and theatres (artists=> great artists).
Defeating the rivals:
Legions are really strong, I trained a lot of them and built roman roads across the whole empire. This way I was able to defeat Arabs on spawn. After the peace period I conquered Spain, France, Germany (Holy Rome??? how they dare?) and Poland. I discovered Poland and gave it to England, so England and Vikings went Protestant. (I didn't want to make an amphibious invasion, since I had only one port in north sea and no port in baltics). In these wars it is essential to raze most cities, else you will control a large amount of useless cities. Few and good cities is the best.
Winning the victory:
The last rivals I faced were Portugal, Mali (converted to catholicism!) and Congo. By 1450AD I had cavalry so conquering happened in a few turns. Building the cities (and some wonders) payed out and I controlled the top five cities. I controlled over 16 cities, enough to build the four cathedrals. After conquering Mbanza Congo I won the religious victory.
Trivia:
When I conquered Poland latin names appeared.
When I built the apostolic palace Orthodoxy was founded in my second city, Milano, while Hagia Sophia was in my capital Rome.
Morocco was orthodox at first.
Alternative strategies:
I could use missionaries to convert some euros to orthodoxy instead of trying to conquer them. However, destroying one civ meant less computing resources, so it is a more ecological option

. Catholic civs spawn from about 700AD (Spain) until 1167AD (Italy). Congo spawns in 1390AD. The next catholic civ spawn in 1810AD (Argentina), but catholicism spread too easily to the new world, so facing a catholic Aztec or a catholic Peru earlier on is propable.
So the best strategy is to destroy all Euros and win before 1390AD. If a euro builds a colonial empire it is possible that catholicism spreads in the new world or in far east.