Agents are game entities with intentional behavior. They have goals which they are trying to accomplish. Accomplishing a goal may bring the agent closer to a game goal, or they can be the highest level of goal the agent can pursue. For example, an AI-controlled army in an RTS is in pursuit of a game goal only accomplished when all enemy buildings are destroyed. To serve this game goal, the agent will have to make the proper decisions of when to attack and when to defend. These decisions are based on smaller goals of attacking the enemy and preserving its army.
Agents determine their goals based on the current state of the game. This may be a state which is local to the agent. For example, in a given FPS, the AI-controlled agents may be patrolling an area. During this time, their only goal is to move from point to point, maintaining awareness of their surroundings. If the player-controlled agent it perceived by the AI-controlled agent, the AI-controlled agent may have a new goal of killing the player-controlled agent. However, if the player-controlled agent is never perceived, the AI-controlled agent may not alter his goals not matter what else is happening in the game.
Agents can also determine goals based on the complete state of the game. For example, in strategy games, the AI-controlled agent has to determine its goals based on its current resources available, as well as how powerful its country/army is compared to enemy countries/armies. Of course, this is also dependent on the amount of information that is available to the AI-controlled agent, but its current goals are based on the analysis of all information available.
Simple entity manipulation is often performed in pursuit of agent goals to create more complex entity manipulation. For example, the simple entity manipulation of moving performed in pursuit of the agent goal of survival is the more complex entity manipulation of evasion.
Tom Clancy's Rainbow Six Vegas
In Tom Clancy's Rainbow Six Vegas, enemy soldiers will pursue several goals depending on the situation. Characters have general patterns of patrol. If they see your character in the open they will begin to fire and yell for help, often times they will take cover trying to preserve their own lives. Their goal may be to maneuver to better locations, try to flank you or throw grenades at your location. In some situations they may choose to kill a hostage in order to sabotage your mission, instead of engaging in a firefight.
The Sims 2
In The Sims 2, based on certain parameters, each Sim has certain goals it needs to meet.
Mortal Kombat 3
In Mortal Kombat 3 for SNES, the player must defeat an enemy agent. The opponents' goal is the opposite: defeat the player using a variety of fighting moves and specials actions.