Class 2 - limit cycles. The system develops periodic behaviours, which then repeat continuously. Class 3 - chaotic. The system becomes aperiodic, continuously changing in unpredictable and random ways. Class 4 - structured.
System can develop in highly patterned but unstable ways.
Computationally rich, e.g. the Game of Life. This denotes an automata between states 2 and 3 - at the edge of chaos , as we call it. The type of behaviour found for a particular CA depends upon the structure of the rules employed. These classes have equivalents in higher dimensional inorganic and living systems, especially Type 4 . Suppose now that we also relax the movement restriction, we then have the more general form of automata used in Artificial Life, and often referred to as Agents or even Creatures.