Within the World, several different kinds of Things exist. You can place the Things where you want them or have them placed in random positions. In the World window, Rocks appear yellow. Each occupies only one Cell and appears red in the World window. The behavior of Critters and how we can modify their behavior is the focus of the course.
Critters can move.
Time in the World is divided into a series of discrete time steps. When the World is running, it goes through a fixed number of time steps. On each time step, each of the Critters in the World has a chance to move. The movement depends on the Critter's current heading and speed. Each Critter starts with a particular heading when it is created, and on each time step, its heading may change depending on whether it turns.