Unlimited Rulebook: a Reference Architecture for Economy Mechanics in Digital Games

In game development, mechanics are one of the basis of the entertainment experience. However, the cost of implementing, improving, and refactoring economy mechanics is high because solutions cannot be easily reused across products. We argue that a reference architecture reduces this cost by providing knowledge reuse in addition to software reuse. To achieve that, we designed Unlimited Rulebook, a reference architecture for economy subsystems in games. It builds on established techniques such as Predicate Dispatching, the Entity-Component-System pattern, and the Adaptive Object-Model architectural style to facilitate the addition and modification of entity types and mechanics to the game while reducing the cost of changing existing code. We evaluated this cost reduction empirically via quasi-experiments with university students in two game programming courses.