I've tried this a few times and it seems pretty successful (at least until next patch).
Deity
Pangea
Quick pace
Random Personalities
No ancient runes
Raging barbs (raging barbs are not vital for this strategy...they are just fun since you get warriors early to deal with them
)
Settle on a luxury resource if you can. This will help you out.
Early build order: Scout->warrior->warrior->worker->settler. Doesn't actually matter that much as long as you get some warriors out. In the end want around 6 warriors. These are going to be rifles eventually. Train them on barbs. You can run off either 2 or 3 cities. Your pick here.
Granaries:
I build them. (Allows you to run 2 specialists in a library with a low pop/no martime ally)
Culture:
You need a monument in both cities up somewhat early. Maybe even a temple eventually. This is a cultural strategy.
Libraries:
You need micro specialists. Also, if you can run 2 specialists in 2 cities you can get 2 GS before you research physics. if you bulb physics AND gunpowder, just make sure you are able to get a third GS out before you reach the dynamite tech.
Research:
You are going to beeline into horseback riding. I have had little success with warrior rushing and I find that I need horses anyways.
HBR->lux->writiing->other lux resource->ironworking->
Collesium tech -> +culture tech (can skip)->
steel working->
physics (if you have 2 GS you might be able to bulb physics as well)->bulb into gunpowder->double bulb into rifling with the 2 free techs from rationalism.
Social Policies:
Rationalism down to 2 free techs->
Order down to +5 production->
Fill out rationalism tree->
+25% combat in friendly lands from order->
+33% combat strength in friendly lands from tradition->
Autocracy (just get the SPs you want
Once you get police state you can annex everything and have that be your last SP. Or you can continue filling trees out.
Useful Wonders:
Forbidden Palace
Himeji Castle
Big Ben
Cristo redentor
Sistine Chapel
Statue of liberty???(dunno if it is worthwhile... Takes too much production)
Strategy:
1. Farm barbs with your warriors to get promotions.
2. Once you get around 4 horses position and DoW on someone nearby.
3. kill units until you get a Great General then take the city. If you want you can take the city earlier but make sure you clear the area. Newly settled cities are a good target. Take some workers if you can.
4. You need gold. Get gold by selling whatever you can. Trade away luxuries/strategic resources. Take the peace treaty gold and DoW again after 10 turns. Do what you can.
5. You need iron. Get a hold on some iron. Settle a third city next to iron if you have to.
6. You should finish off 1 civ with just 4 horses and a great general. I would promote 2-3 horses to medics and other 1-2 to shock 2. Spam trading posts in captured cities.
If you get longswords before your hoses are done feel free to bring them in to help out. Feel free to start war with another civ.
7. Once you bulb rifling:
You need at least 1 cultural ally. More is better though.
You really need at least 1 maritime ally. Without one I feel like I get behind. If you get it once you get rifling you should be okay. Don't be afraid to take out city states to get others to ally you.
USE THOSE RIFLES. Start war with another civilization. You should have a GG ready for the rifles. Nothing is going to stop 2 promotion rifles with a chinese GG this early on.
8. Tech to education
9. Tech to fertilizer and bulb dynamite with a GS to get to industrial
10. Go for order and get +5 production as soon as possible. Then fill out the rationalism tree.
11. Beeline to the forbidden palace and build it. Prepare your production city by improving production tiles beforehand. Usually my capitol will build the palace. Use an extra GG to start a golden age and build a windmill before you build the palace.
12. Promote your horses to knights and cavalry when you can. Your horses are still going to be very strong for a long time.
13. I don't think I need to tell you this, but electronics is the next step
MODERN WARFARE:
You need the +33% and +25% bonus in friendly territory from tradition and order. You need to turtle until you have enough troops.
If you are going for a domination victory chances are that you will need to get GDRs to win unless you were able to take out enough with your mechanized infantry. Make sure you build all the +xp buildings and a heroic epic. If you have a lot of gold (like 4000 or so) and you have Big Ben(maybe even without Big Ben...), get the -33% cost when purchasing from autocracy, buyout 4-5 modern armors, and start producing mass mechanized infantry. Mechanized infantry are not enough to hold open ground even in friendly territory with every possible +friendly combat bonus. Rocket artillery can help but I am not a fan of them. I usually get 1-2 max.
Hold the fort until you get GDRs (well, you can go with a fleet of highly promoted modern armors (shock 3/blitz/autorepair)) then rush buy a couple of them if you can. Once you have a good amount of GDRs you can push out. GDRs in friendly territory will almost never die.
As an alternative if you find a back door I think you can sneak into the last civ's base and take their capitol. I never tried it though.
For now, this seems to be a very power strategy if you can pull it off correctly. The only downside to this strategy is that you need to get at least enough gold to ally 2 city states relatively early. This can be challenging sometimes. Finding a maritime city state is also no easy business sometimes. And if you don't get a maritime CS I just feel like you get behind because they are just so powerful.
NOTES:
Forbidden Palace: You should be able to get this every game. AI builds it pretty late most of the time.
I like culture so I don't settle a lot of cities. Usually 3 max. Also, the AI gets really pissy when you start settling a bunch of cities. If you just conquer and puppet they don't seem to care as much.
Universities and Public Schools should go down pretty fast so you stay ahead on the science front.
Once you get coal trade it all away except for the 2-3 coal you need for factories in your 3 cities.
Try and stay
so your cities can keep growing. Growth is good.
Build the +XP for all land units building. The difference between a doubly promoted artillery and a non promoted artillery is huge.
Deity
Pangea
Quick pace
Random Personalities
No ancient runes
Raging barbs (raging barbs are not vital for this strategy...they are just fun since you get warriors early to deal with them

Settle on a luxury resource if you can. This will help you out.
Early build order: Scout->warrior->warrior->worker->settler. Doesn't actually matter that much as long as you get some warriors out. In the end want around 6 warriors. These are going to be rifles eventually. Train them on barbs. You can run off either 2 or 3 cities. Your pick here.
Granaries:
I build them. (Allows you to run 2 specialists in a library with a low pop/no martime ally)
Culture:
You need a monument in both cities up somewhat early. Maybe even a temple eventually. This is a cultural strategy.
Libraries:
You need micro specialists. Also, if you can run 2 specialists in 2 cities you can get 2 GS before you research physics. if you bulb physics AND gunpowder, just make sure you are able to get a third GS out before you reach the dynamite tech.
Research:
You are going to beeline into horseback riding. I have had little success with warrior rushing and I find that I need horses anyways.
HBR->lux->writiing->other lux resource->ironworking->
Collesium tech -> +culture tech (can skip)->
steel working->
physics (if you have 2 GS you might be able to bulb physics as well)->bulb into gunpowder->double bulb into rifling with the 2 free techs from rationalism.
Social Policies:
Rationalism down to 2 free techs->
Order down to +5 production->
Fill out rationalism tree->
+25% combat in friendly lands from order->
+33% combat strength in friendly lands from tradition->
Autocracy (just get the SPs you want

Useful Wonders:
Forbidden Palace
Himeji Castle
Big Ben
Cristo redentor
Sistine Chapel
Statue of liberty???(dunno if it is worthwhile... Takes too much production)
Strategy:
1. Farm barbs with your warriors to get promotions.
2. Once you get around 4 horses position and DoW on someone nearby.
3. kill units until you get a Great General then take the city. If you want you can take the city earlier but make sure you clear the area. Newly settled cities are a good target. Take some workers if you can.
4. You need gold. Get gold by selling whatever you can. Trade away luxuries/strategic resources. Take the peace treaty gold and DoW again after 10 turns. Do what you can.
5. You need iron. Get a hold on some iron. Settle a third city next to iron if you have to.
6. You should finish off 1 civ with just 4 horses and a great general. I would promote 2-3 horses to medics and other 1-2 to shock 2. Spam trading posts in captured cities.
If you get longswords before your hoses are done feel free to bring them in to help out. Feel free to start war with another civ.
7. Once you bulb rifling:
You need at least 1 cultural ally. More is better though.
You really need at least 1 maritime ally. Without one I feel like I get behind. If you get it once you get rifling you should be okay. Don't be afraid to take out city states to get others to ally you.
USE THOSE RIFLES. Start war with another civilization. You should have a GG ready for the rifles. Nothing is going to stop 2 promotion rifles with a chinese GG this early on.
8. Tech to education
9. Tech to fertilizer and bulb dynamite with a GS to get to industrial
10. Go for order and get +5 production as soon as possible. Then fill out the rationalism tree.
11. Beeline to the forbidden palace and build it. Prepare your production city by improving production tiles beforehand. Usually my capitol will build the palace. Use an extra GG to start a golden age and build a windmill before you build the palace.
12. Promote your horses to knights and cavalry when you can. Your horses are still going to be very strong for a long time.
13. I don't think I need to tell you this, but electronics is the next step

MODERN WARFARE:
You need the +33% and +25% bonus in friendly territory from tradition and order. You need to turtle until you have enough troops.
If you are going for a domination victory chances are that you will need to get GDRs to win unless you were able to take out enough with your mechanized infantry. Make sure you build all the +xp buildings and a heroic epic. If you have a lot of gold (like 4000 or so) and you have Big Ben(maybe even without Big Ben...), get the -33% cost when purchasing from autocracy, buyout 4-5 modern armors, and start producing mass mechanized infantry. Mechanized infantry are not enough to hold open ground even in friendly territory with every possible +friendly combat bonus. Rocket artillery can help but I am not a fan of them. I usually get 1-2 max.
Hold the fort until you get GDRs (well, you can go with a fleet of highly promoted modern armors (shock 3/blitz/autorepair)) then rush buy a couple of them if you can. Once you have a good amount of GDRs you can push out. GDRs in friendly territory will almost never die.
As an alternative if you find a back door I think you can sneak into the last civ's base and take their capitol. I never tried it though.
For now, this seems to be a very power strategy if you can pull it off correctly. The only downside to this strategy is that you need to get at least enough gold to ally 2 city states relatively early. This can be challenging sometimes. Finding a maritime city state is also no easy business sometimes. And if you don't get a maritime CS I just feel like you get behind because they are just so powerful.
NOTES:
Forbidden Palace: You should be able to get this every game. AI builds it pretty late most of the time.
I like culture so I don't settle a lot of cities. Usually 3 max. Also, the AI gets really pissy when you start settling a bunch of cities. If you just conquer and puppet they don't seem to care as much.
Universities and Public Schools should go down pretty fast so you stay ahead on the science front.
Once you get coal trade it all away except for the 2-3 coal you need for factories in your 3 cities.
Try and stay

Build the +XP for all land units building. The difference between a doubly promoted artillery and a non promoted artillery is huge.