After playing a few games on Emperor, I found the following strategies works for me to win the game (either by spaceship or by eliminations)
Strategy for Emperor
- build a militia
- build a settler
- try to develop the wheel as quickly as possible. This will allow you to build a few chariots to explore and eliminate neighbouring civs quickly to get you the geographical advantage. This is very important.
- Build cities on strategic areas relative to the enemy location (such as a narrow junction) to block off access from other civs.
- For most cities, you need only 1 militia/phalanx. You'll need 2 or 3 for those near the ocean (against barbarian ships), and 3+ with a chariot/catalpult on critical cities closest to other civs.
- Keep building settlers and militaries to attack until you get about 20 cities. You will probably need this many cities to catch up with over civs scientifically.
- If your landmass is too small, build triemes to build more cities on other islands.
- Don't build Granary, or else you get too much civil disorders b/c of growing too fast. Build temples as your first development, then cathedral (i.e. once your city is militarily secure).
- If you get a civil disorder, try converting a square to an entertainer to maintain productivity in the city.
- once your treasury is about $250 or so, put tax/lux rate to 0% so that you develop fast scientifically. Your objective is to get about 5 to 6 discoveries per turn before 1AD.
- Increase your tax rate to "break even" financially if you are getting below $100.
- once your cities finish building temples, (and cathedrals for cities > size of 5 or 6), then you can build caravans to help build wonders.
- wonders that are good to have: JS Bach Cathedral, Great Library.
- Try to aim to develop Railroad pretty fast, so that your city can grow easier by needing not many squares.
- You should be able to get the 20 cities by 1AD. Switch government to Monachy. If you have Republic, switch to Republic. Once do so, you should get < 10 turns per discovery.
- Your kingdom is pretty much set from this point. build more caravans for wonders. Get the SETI program, and Apollo for Space ships
- Switch to communism if you want to eliminate other civs by war.
There are a lot of minor tricks, but this should at least get your civ to survive or even win well in Emperor mode.