The advent of widely available digital computers completely changed the possibility horizon for those who wished to simulate real-world and theoretical problems. Instead of using analytical mathematics with all its inherent simplifications people were able to use credible approximations and get agreeable results within reasonable time-scales. One class of models called Cellular Automaton (CA) models are particularly interesting because they operate by the repeated application of an apparently simple set of rules and can appear to deliver results which are incredibly close to what is observed in nature. Stephen Wolfram of Mathematica fame did a pretty good job of cleaning up the entire subject in one-dimension. Conway’s Game of Life is the classic example of a two-dimensional CA. Of course, there is still the question of whether these are real or just like a murmuration of starlings at dusk.
TLM (Transmission Line Matrix) is a set of transition rules that can be thought of as an automaton modelling scheme, but it is more than that, because unlike most CAs these rules are firmly grounded in the laws of electromagnetics. The Theory of TLM and some simple Implemenation of TLM can be accessed in my books.