). To simulate evolution better, give the enemies a set of properties(e.g. health, defense, food needed to stay alive, intelligence, camouflage abilities). the animals then wander the world, eat when they need to(when less food than needed) and so on. every now and then(using a random timer) they reproduce. reproducing produces 1 new animal BUT it's properties are changed slightly. the properties from the parents are averaged and then have a small random change made to them and given to the new animal. However, this system requires a natural predator-to create evolution pressure, so that only the animals with the highest health, best camouflage etc will survive and over time the average stats of each animal will get better- and a food source for the animals so that the population will be limited by food. in Factorio this could be implemented by using the pollution factor to increase the random mutation at time of reproduction, biomes to set the available food in an area-dictating the number of enemies around- and a new creature that will hunt the biters/spitters and also the player.
This may be quite taxing on weak computers though, as the stats for each individual animal will need to be recorded
.