Multiplayer is becoming increasingly popular as the patches become more stable. Another popular way of playing by joining a ladder which gives you a rank among other players. After playing hours of online I have developed a series of strategies to help you win a greater number of games 
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First thing you have to consider is most games are played with a time limit. Usually about two and a half hours is the standard with three hours being the longest among most people. Knowing this you have to realize that you will not get much beyond Ancient Age if you pass it at all. So you have to throw out your single player strategy and conform to a strategy that gives you the best possible advantage in the shortest possible time.
What kind of game are you playing??? The general setup for MP and ladder games are Pangea, Regent, Elimination, Tiny or small (depending on number of players) but these do change from group to group so understand how your strategy will work for each style of game. For example elimination games should be played different than a normal game.
Increased warfare… Especially in ladder games you will rarely spend the entire game at peace. Trust noone even if you are offered an alliance…especially if they offer you an alliance. If you are a peaceful builder you may have trouble playing online.
Who should I play with..? I would recommend playing with an civ with ancient age UU. Mainly because they give you the greatest chance of getting a golden age. Other than it is up to you and your style but I found that Egypt (for points) and Carthage (for elimination) are the best civs. Persia is second but if you find yourself without iron your S.O.L.
In the beginning… The start location can make or break your game but remember a bad location does not mean all is lost. Even if you start behind in points you can always recover given enough time. Develop an opening sequence of play that is the most efficient…DO NOT WASTE A TURN OF PRODUCTION This may seem obvious but if it takes 4 turns for your city to reach size 3 and 3 turns to build a settler you will have wasted a turn of production.
First turn.. Build your city immediately do not waste time looking for a more suitable location if you do you will fall behind in points. Start locations can be overcome. After building your city and putting your worker to work quickly get to your science advisor and click on a tech you wish to research (I recommend Bronze working for elimination games and Ceremonial Burial for all others). Then as quick as you can get to your domestic advisor and move your research to 90 percent. This will give you a turn advantage in techs. I usually begin by building 3 warriors 2 of which I send as scout. Then I build a settler. I then build two more warriors (or spearman if I have bronze working) then another settler..Under no circumstances should you send a settler alone…you lose valuable points if he is killed or your city is destroyed by another player. Do not build improvements
Pack em tight Build your cities very close to one another only about three squares away if possible. Rarely will your city get beyond size 6 unless it is by a river…even then this style can support a few size 12 cities. This close building will help in defense of your empire (important in elimination games) and also in corruption. Make sure you have a good supply of workers going to help with infrastructure. Again you must be able to create the greatest amount of production in the shortest amount of time. Never spread your cities too far and never leave a city unprotected. Make sure you have at least one defender (spearman) and one attacker (archer, horseman, or swordsman). A popular tactic is for a player to move a spearman or 3 defense UU through your empire destroying roads, mines, and irrigation. If you don’t have an attacker you may get caught with your pants down. Don’t worry about barracks or temples until you have build the number of cities you are comfortable with. After which you may pop rush both the temple and barracks (granaries in towns by a river otherwise don’t bother). Then concentrate on your military.
Techs only a few techs are vitally important in a MP game. Again you will often only play a short time and in ladder games other players will rarely trade techs with you unless you are playing teams or have an alliance. Even so as your army increases in size your ability to research will diminish so my advice is to pick 4 or 5 techs you absolutely need then forget about the rest. After researching your techs immediately switch all your resources into luxuries. Again this will help your score.
governments NEVER change your government…even if you decide you want the hanging gardens do not change over another government since you will waste valuable time in anarchy which could make or break your game. Even if your religious I’ve found that no other government can handle the large army your bound to posses as Despotism can. Plus the pop rush is second to none.
Bait and switch Elimination is a very popular mode of play since even someone who is far behind can win if they build a proper military. One tactic I like to use is very effective. Build two armies with stacks of swordsman (if possible) and another with horseman or archers (cheaper). Move up to one side of the player’s empire with your cheaper military and draw his military to that side. Then sweep around with your swordsman to his most recent city on the other side and watch him squirm.
The Rush/ The Choke A popular strategy within the online community is do a Aztec or Zulu rush. I have to admit that I would find myself falling victim to it and it seemed undefendable.
The Strategy For those who aren’t familiar, The Rush or Choke is when early in the game another player sends a large stack of Jaguar Warriors or Impi to destroy you or serious hinder your progress.
How to defend it may seem tempting to build spearman at the beginning of the game and I use to do this as well…but as I found out this only makes the situation worse. Look at the units that are involved in the rush they posses a one attack while spearman have the ability to defend well enough it is doubtful you will counter attack with them (one they are expensive and two you won’t have many)…which brings me to my next point, Warriors are cheaper and you can build more cheaply than spearman (20 v 10 shield).
The Scenario (Jaguar Rush) A group of 5 to eight Jag comes into your territory and unless your retarded you know he’s coming for you. As most games played online are elimination (if you lose one city you lose the game) that city must be defended…hopefully you have build roads connecting your other city or cities. Pop rush a wall quickly and fortify those 3 or 4 warriors you have already premade. Move any spare units into that city and fortify…this may leave your other cities lightly or undefended but that’s a risk your going to have to take since you cannot lose that city. By now you should have at least 4 to 5 warriors fortified (+25%) if you were smart you built your city on a hill (+50 %), and the wall gives another (+50 %). So now instead of a 1 defender warrior you have 5 2.25 defenders. So the Defender has a 92.3 percent chance of winning (Spearman have a 98 percent only 6 percent increase). The attack happens and he loses about 2 to 4 jag warriors with only 2 to 4 left (jags have retreat ability)…so now you can clean up with the other warriors you have and have built during that turn. Again even though spearman are a tempting choice in this situation you lose a kind of flexibility.
Impi Choke Impi rush is generally an entirely different and less scary strategy but still effective…This strategy is based on keeping an opponent from expanding by destroying roads, mines, etc and to get them too scared to build any settlers. Again this strategy is thwarted by (sound of bugle) THE WARRIOR. The imp is more expensive than a jag so expect only 2 or 3 to come into your territory and you should always have about 3 or 4 warriors in a city at a given time. So pop rush that wall (if you haven’t built it) to deter an attack and move your warriors to defend your mines and roads…You may think "I gotta get an archer out" not so fast because before you can he will kill himself attacking your warriors or at least hurt himself greatly (remember you still get bonuses for terrain and fortify). So now if he’s not dead he’s hurt and you can clean up with the other warriors you have built or have defending. Luck plays a part and he may get to an improvement (that two move is deadly) but he won’t be their for long with this strategy.