Cellular Automata are a fantastic demonstration of how a simple set of rules can elicit a complex emergent behaviour. In this video I show John Conway's Game Of Life implemented in quick and simple C++ at the command line.
Github: https://github.com/OneLoneCoder/Javidx9/blob/master/ConsoleGameEngine/SmallerProjects/OneLoneCoder_GameOfLife.cpp
Blog: http://www.onelonecoder.com