The Basics
Most people will learn the game via the map itself. The first two minutes of the game include a short but detailed explanation of how to play. Do not forget you can review instructions ingame by pressing PAGE UP on your keyboard.
OBJECTIVE:
In "Fort Wars", each player starts with a single Fort building. This is where you receive units for free or from purchase. You lose if your fort is destroyed. Kill all enemy forts and you win. As a bonus, every time you kill a fort, you receive Super Ronin units to your army.
KILLING AND GETTING COIN:
The currency used in the game is COIN. Coin is gained through fighting and killing enemies. The more kills you get, the more Coin you receive. You can have a maximum of 100 coin at a time. This currency allows you to both spawn better units and purchase upgrades/items from the STORE ISLAND.
SPAWNING SOLDIERS:
The first question that probably comes to your head is how to select your units being spawned. The farthest and smallest island from your fort, which has units that belong to you, is the SPAWN ISLAND. This island is where you choose what comes out of your fort for free. Simply move one or two of the units on the island to the Native Hut. Now that unit type will begin to spawn at your fort. You can have a maximum of 2 unit types around the Native Building at a time.
Which units should you choose? In all Age of Empires games, the general COUNTER SYSTEM is Ranged > Melee > Horses > Ranged. AOE3 added a little bit of complexity by introducing artillery (beats everything but horses) and ranged horses (counters horses).
The more Coin you have, the better units you get to spawn, so it's a balance between saving for better spawn vs upgrading and buying.
BUYING AND UPGRADING:
If you ever wish to get better, you MUST purchase and upgrade. Not doing so is the same as "never leaving Age 1 in Supremacy", as Matei once said.
First you must locate your STORE ISLAND. This is the middle island between your SPAWN ISLAND and the mainland. To buy stuff, move what you want to buy to the Fort Tower at the top. Each unit on the island represents something you can buy - upgrades, special super units, even special powers!
The main ones you should care about are Attack, HP, and Speed, which are all on the left side of the island. The horse is Speed. John Adams is HP. Beaumont is Attack. One more you want to know is Super Speed, which is the bear with a cape, and will often prove pivotal for winning games. For a full list, move George Crushington, the GIANT BREATHING STATUE, to the Fort Tower.
Unit costs are displayed by holding your mouse of a unit's icon (when the unit is selected).
AWARDS:
One may notice that as the game goes on, your food and wood increases. What does this mean?
Food - this is the number of units you've killed.
Wood - this is the TOTAL number of XP you've gained, which is more for expensive kills.
Every certain number of kills or XP, you will receive a choice of 3 awards. Kills give you something free. XP on the other hand, offer new STORE ISLAND options. This will allow you to purchase items your opponent may not. This is like a tech tree or choice of build order.
Awards will be given on the islands at the top and bottom of the map. The North Island is for XP awards while the South Island is for kill awards.
THE CENTER:
As soon as the game starts, many will notice a spotlight in the middle of the main island. In that spotlight is a seemingly insignificant llama. But it's in the SPOTLIGHT. Why?!
That is because this is no "insignificant" llama. It is the MIGHTY llama and a very significant one indeed. Capturing this llama will provide you with FREE trickle of Coin, giving you quite the upperhand over your opponents.
As the game goes on and the llama grows fatter, it will give away more Coin at a time. So be sure to capture it when you can!
CIVILIZATION CHOICES:
Yes! The civilization you choose at the beginning of the game DOES matter! Each civilization is given a unique bonus. Some may be able to make the most of it, others may prefer to try other civilizations. Every few minutes, reinforcements also come to your fort. These are also unique to your civilization - often it will be the civilization's special artillery (for example Ottomans have the Great Bombard), or a Heavy Cannon if your civilization has not a special artillery. With that also comes the civilization's special mercenary. Each civilization has their own type of mercenary - some have Jaegers....
See a list of civilization bonuses, spawning stats, and more on the Statistics page!
* Note: clarification on Asian/DLC civs - the map won't break or put you at disadvantage, you just will be normal without any bonuses but also no weaknesses.