Hit the green button. Hover over creatures to see there code. Change the food spawn rate, less = more. This is similar to a genetic algorithm. The creatures you see have energy, shown by there size. they are trying to get to the green dots, food. They get energy from eating the food and fighting. they can mate, fight, run, eat and evolve. Its the survival of the fittest. If the population gets below 30 a new random creature spawns.
inspired by https://www.youtube.com/watch?v=jAQNiL3o5lU