Paper: A Survey on the Need and Use of AI in Game Agents

Sule Yildirim and Sindre Berg Stene. 2008. A survey on the need and use of AI in game agents. In Proceedings of the 2008 Spring simulation multiconference (SpringSim '08). Society for Computer Simulation International, San Diego, CA, USA, 124-131.

This paper is a good survey on the use of various AI methodologies in commercial video games. They found that the most commonly used AI methodologies to achieve game AI can be stated as follows:

* Decision trees: can be realized by If-Then statements..

* Fine state machines

* Command hierarchies

* Manager task assignment

* Path finding (A*)

* Terrain analysis

* Influence mapping

* Formations

* Flocking

* Emergent behaviour

* Artificial Neural Networks 

* Genetic Algorithms

* Fuzzy logic

One of the most interesting AI approches listed above is emergrnt behavior. This kind of AI has been explored in Black & White.

Also, they present a misture of needed AI depending of the type of game. For example, In RPG games, a team is built up to reach a common goal. The intelligence required from a team or from individual characters depends on how complex it is to reach to the common goal.

Paper: Enemy NPC Design Patterns in Shooter Games

Gabriel Rivera, Kenneth Hullett, Jim Whitehead. Enemy NPC Design Patterns in Shooter Games (2012). Proceedings of the 1st Workshop on Design Patterns in Games.

This paper presents design patterns for NPCs in shooter games and explores their effects on gameplay.


Elements of an NPC
- Movement Type:
     * Flanking Intensive
     * Passive
     * Slow Push
     * Rush
     * Cautious
- Movement Range - This is how far the NPC will move during an engagement. This can be Low, Medium, or High.
- Movement Frequency - This is how often the NPC will change their position during an engagement. This can be Low, Medium,
or High.
- Attack Frequency – This describes how often the NPC will initiate an attack. This can be Low, Medium, or High.
- Weapon Type:
     * Sniping Weapon
     * Close Blast
     * Assault
     * Weapon Projectile
     * Power Weapon
     * Melee Weapon
- Weapon Damage – A general indicator on how much damage the NPC will do to the player’s Health, Shields, or Armor. This can
be Low, Medium, or High.
- Armor/Health – This denotes how much damage the NPC can take before being killed. This will typically be linked to how hard
the NPC is to defeat. This can be Low, Medium, or High.
- Motive:
     * Challenge – The degree of difficulty within a combat encounter.
     * Tension – The degree of mental stress the player experiences during a combat encounter.
     * Pacing – The degree of movement that the player will engage in during a combat encounter.

Structure Patterns of NPC Design
     Name - The name of the pattern should describe what the pattern does essentially.
     Description - A brief description of how the pattern is typically used and the effect it has on gameplay. This can be seen as the primary role of the enemy NPC.
     Affordances – This section lists the elements of the NPC and what those elements can be broken down into.
     NPC Relationships – Description of any special relationships with other patterns. This includes an Enemy NPC switching to a different pattern.
     Examples - Some examples from well-known games