Procedural content generation in games
Procedural Content Generation (PCG), a.k.a. procedural generation or random content generation, is a term to describe the creation of content algorithmically "on the fly" (i.e. after the software executes, rather than before). In digital games it is generally used to generate random content (like textures, objects, NPCs, or levels), and to reduce file size. It generates new content every time the player starts the game. It is the difference between loading a set of 1,000 individual models in a game battle, and generating them at the time that they are needed.
The concept of randomness is the key: procedural content generation should ensure that from a few parameters, a large number of possible types of content can be generated.
PCG Games
Many games use procedural content generation to increase the length of game play, some of which are free to download and play. The most common category of PCG games is roguelikes, which have a long tradition of using procedural content generation techniques.
The following games feature procedural content generation as a main feature of the game play:
Angband
Diablo 2
Dark Cloud
kkrieger
Spore
The game kkrieger can be considered "overkill" with procedural generation: everything in the game is generated dynamically. Because of this, the game takes up only 96 kilobytes, while a conventional game equivalent to kkrieger would use upwards of two or three hundred megabytes.