It is a Simulation

One particular philosophy the game tries to stick with is the concept of emergent gameplay through expressing individual systems of interaction rather than directly dictating mechanics. For example, suppose we want a way to model resource growth. A simple method is to have clear numerical values for resource/second based on some combination of factors. Prosperity took a more complex route: resources are created when it is harvested, refined, by some group of workers. Each worker contributes some amount of work, which is derived from some independent variables. A piece of work produces some resource once it is done. This means the mechanism of resource growth and predicting resource growth is itself emergent from more fundamental rules. This piece of logic is complex but it opens up the game to a number of new possibilities - for example having some way to affect production output by making people happier, or considering trade-offs between the happiness of one group of workers with the happiness of another group. We could now model complexity or effort required to do some work based on variables like seasonal changes, migration patterns, maybe even availability of water. When gameplay is emergent from some set of rules that expresses a simulation of a world, the gameplay itself can be wildly different time after time.