GAMEPLAY
Age of Empires Online, like its predecessors, was a real-time based strategy videogame. The game featured much of the gameplay of past games in the series, with the addition of a massive multiplayer online gaming element. The player possessed a capital city for each started civilization, that continued to exist when the player was offline. Also, the game featured a great quantity of new content, such as the ability to craft items with earned materials and trading with other players.

The main gameplay revolved around the player being able to develop a civilization from its birth to its peak and fall. To assure victory, the player had to gather resources which could be spend on new units, buildings and more advanced technology. Resources also had to be preserved, as no new resources became available as the game progresses. A major component of the game was the advancement through four ages with each advancement bringing new technologies, weapons, and units.

Civilian units, called villagers, were used to gather resources. Resources could be used to train units, construct buildings, and research technologies. The game offered four types of resources:
  • Food
  • Wood
  • Gold
  • Stone
Food was obtained by hunting animals, gathering berries, harvesting livestock, farming and fishing. Wood was gathered by chopping down trees. Gold could be obtained from either gold mines or through trading and stone was collected from stone mines. Villagers required depository buildings; a town center, dock, storehouse, or for the Babylonians, an ox cart, where they could store gathered resources. Each civilization could research upgrades that increased the rate of resource gathering.

Players could construct a market for trade; enabling them to either trade wood, stone, and food for gold, and use gold to buy other resources. Market prices fluctuated with every transaction (supply versus demand). Furthermore, markets and docks could generate gold, by sending trade units (caravans or merchant transports) to visit own or allied town centers and ports. Once the trade units returned, gold was added to the stockpile with the amount of earned gold being related to the distance traveled.

Units

Age of Empires Online included five classes of military:
  • Infantry
  • Archers
  • Cavalry
  • Siege weaponry
  • Naval units
All military classes were developed to maintain a balance on gameplay, and thus avoiding visible advantages between civilizations. As an example, a unit powerful against buildings could be weak against a certain kind of cavalry. Unique units were available for the Greek, Egyptian, Celts, and Persian civilizations, either from the start of the game or through advisor cards. These civilization-specific units were generally more powerful, but could still be vulnerable to certain units. The priest was a special kind of military unit that had the ability to convert enemy units to the player's civilization, and to heal allied units.

Every player had a limit to the total number of units they can create—a population limit—but generally could not immediately use this entire population. The population limit increased with the number of houses or town centers in the player's village to a maximum of 200, with each house contributing five (or ten for the Norse) and each town center contributing 20 to the limit. There were two important features for unit management: The idle villager button, which helped players identify villagers that have not been assigned a task, and the town bell, which send all of the player's villagers into the nearest town center, fortress or tower for safety.

Buildings

The buildings in Age of Empires Online were either economic or military buildings. Buildings could research technologies and upgrades that increased economic, military or unit-based efficiency, as well as providing resources to the player. Each civilization had unique buildings, but some were common for all civilizations; the most important of these being the town center, where villagers were created, resources were stored, some technologies researched and in which the player could advance to the next age. The town center could fire arrows at enemy units within range. Other economic buildings available included the storehouse for resources, farms, docks (the dock also produced several military ships), and houses to support a higher population.

Military buildings included unit-producing buildings such as barracks, archery ranges, stables, and fortresses, as well as defensive buildings such as walls and towers. Military buildings could perform research to improve the abilities of military units, increasing their strength, defensive capabilities, or other attributes. The fortress was a powerful defensive building which could train a variety of units, including the civilization's unique units, and fired arrows at enemy units within range. It could only be built after a player had reached the third age. There were two other important defensive buildings: Walls and towers. Walls were used to prevent access for enemy units to an enclosed area, while friendly units could traverse the walls through inserted gates. Towers were equipped with the ability to fire arrows at enemy units, or garrison friendly units for protection, and could be used in conjunction with walls in establishing defense lines. Watch posts were used for extendings the line of sight.

Capital city

The capital city was similar to the "Home city" concept implemented in Age of Empires III. The city functioned as the player's home base for their civilization. It continued to exist even when the player logged out of the game, though it could not be attacked or altered by other players. Through the capital city, the player could manage quests, improve technologies, send mail, craft items, participate in player to player trade, acquire and equip new gear for individual units, and visit other player's cities. Stores built within the city could be visited by other players and currency used for the items purchased would be added to the player's funds. Unlike the home city from Age of Empires III where you could only customize the look of buildings, the capital city was completely customizable; buildings and rewards could be placed anywhere on the city map as the player chooses.

Players could add buildings, rewards, houses as well as statues and bushes along with other things to decorate their capital city. "Vanity Island" existed to add new bushes and statues for the player to use to decorate their capital city. The city was also used as a gateway to other AI controlled cities within the region, where a player could visit and acquire new quests and items. The capital city also had many different buildings that the player could build. Craft schools, built from the city, produce gear and consumables for the player to use. Additionally, Microsoft released a crafting app for Windows Phone which a player could use to assist in crafting within the game.

Quests

Quests were the main PvE aspect of the game. Quests generally involved fighting and defeating the AI player. They were similar to the campaigns in previous Age of Empires games. They were completed when the objectives were met. Objectives in quests varied greatly, some quests involved defeating enemies, others involved protecting a building or unit, and some involved collecting a certain amount of resources while defending from the enemy.

Quest rewards included experience points, gold, empire points, chests, and sometimes gear. Certain quests also had a co-op option, which allowed the player to do the quest with another player to help them. Certain quests also had an "elite" version, which allowed for the player to gain a greater amount of rewards, but were more difficult presenting the player with a greater challenge. The different civilizations also had different quest lines, e.g. the Celts had 80 unique quests that the other civilizations do not possesed.

In June 2012, a free endgame content pack called "alliance wars" was released. The content was designated towards level 40 players, and consists of team-based competition revolving around three separate alliances. Players were able to align themselves with a particular alliance and complete quests for powerful rewards and passive bonuses. Contests were also held at daily, weekly, and monthly intervals.

PVP

Player versus player, or PvP, was another aspect of the game. PvP in this game could be started in one of two ways: By using Sparta PvP to find a random match, or by using the arena in the capital city to play against a party member. Sparta PvP could be accessed by visiting the Sparta region in the world map. In Sparta PvP, there were two different types of PvP options:
  • Standard PvP was the first option and allowed the player to use star techs from their tech-tree as well as any gear and advisors that they have equipped in their capital city. This PvP option was first to be released.
  • Champion mode PvP was the second Sparta PvP option. This was also sometimes known as ranked PvP while Standard PvP was known as unranked PvP. In this PvP option all gears, star techs and advisors were disabled and could not be used to start the players off at an even footing. All gears equipped would provide the units with a cosmetic change but would not affect their stats like they would normally do in PvE missions
In Sparta PvP, the player started off with a minimal amount of resources, a few villagers and their scout. Map selection was random and could not be chosen by either players. Champion mode PvP results would also determine your TrueSkill ranking which was used to determine a player's rank globally as well as to help find the player a match and opponents for PvP. In Sparta PvP there was an option for 1v1 PvP and 2v2 PvP. Rewards from Sparta PvP included experience points, empire points, gold and Sparta points which could be used in the stores in Sparta for chests, gear and consumables.

PvP was also accessible through the Arena in the player's capital city. While identical to Sparta PvP in many ways, Arena PvP could differ in many ways. In Arena PvP, you could play against any human opponent in your party as well as choose the map and teams (if it is a 2v2 match) before starting the game. Arena PvP would not affect your Sparta PvP Trueskill ranking. Finally, arena PvP also did not provide any rewards to the winning player. The August 2012 update also added a new spectator mode option for Arena PvP and the October 2012 update made Arena PvP (Standard or Champion mode) free for all players.