Algorithmic Terrain with Cellular Automata
3-color 2D totalistic CAs generate changes in height from a baseline value, totaling over a number of steps of evolution of the rule. Essentially the value of the CA at a given location is totaled through the time dimension, like a local random walk. Different rules, initials, and steps then generate a variety of types of terrain. There are over 1 billion 3-color totalistic rules of this type.