An NPC, meaning non-player character, is a term used when talking about characters or creatures in a video game controlled by a computer. They can be enemies, allies or just people walking in the streets.
This is an example of some enemy and civilian NPC’s from Assassin’s Creed.
NPC’s require specific data to move intelligently, find hiding positions and navigate the terrain. They need to be able to identify all potential cover locations where an enemy can hide, they must be able to analyse the 3D topology so that they know where to flank and not to walk through buildings.
Accurate World navigation is also known as path finding.
World navigation is divided into 2 main categories, world navigation, which takes care of the geometry in the whole of the environment using very specific paths to control the AI, and local navigation, in which the AI must be able to interpret changes in the layout of the level, and then react accordingly. NPCs may have moved or objects have obstructed the paths usually used by the AI, so now Local Navigation has to navigate the NPCs through the objects obstructing the path. The problem with local navigation is that if there are multiple NPCs heading to a single location, they usually end up on the same path with unusual effects.
To deal with this, a flocking algorithm is used. This stops NPCs from colliding with each other by varying the paths used by the AI.
Peter Molynuex suggests that AI will change the way games are designed. It is his opinion that if a game is not fun anymore then gamers will not want to play it. He believes that if you put emotion into AI, then the NPC’s will be able to care and feel, and maybe you can even care back.
Jess Crable suggests that there can can be to much realistic AI in a game, believing that if the AI is to good it can take away from the fun of the game. There has to be a good balance between randomness and believability and some level of unpredictability within straying to far from believable.
Emergent Gameplay is creative use of a game not intended by developers, this could include glitches found by players, or unexpected quirks in the AI, or even a realistic economy that can be found in some online games.
Chess can be considered emergent gameplay because it can be unpredictable, with a near endless combination of moves to be made, the players will have a different experience every time.
These are a few examples of emergent gameplay
Crysis
EVE Online
Filed under: Games engines
