The Open and the Closed: Games of Emergence and Games of Progression

Jesper Juul's paper proposes a conceptual framework for understanding computer game structure by distinguishing between two fundamental approaches to presenting challenge: emergence, in which a small set of simple rules combines to produce large variation, and progression, in which challenges are introduced serially and their solutions are explicitly specified by the designer. The central argument is that most computer games blend these two structures, and that the variation found in complex games is a non-obvious but systematic consequence of their rules rather than mere randomness or player input. Juul grounds the concept of emergence in the science of complexity, drawing on definitions from John Holland and Mark Bedau, and distinguishes between strong and weak forms of emergence.

The paper refines the notion of emergence in game design by separating three types: rule interaction, such as rocket-jumping in Quake III or proximity mine climbing in Deus Ex; combination, the broad space of possible states a rule set permits; and emergent strategies, which are not immediately deducible from the rules and include rules of thumb as well as dominant strategies. Juul argues that emergence should be defined analytically rather than by whether designers anticipated a behavior, since predictability is a poor criterion. He also notes that open systems still tend toward regular patterns, as when Counter-Strike almost always produces fighting or Monopoly always ends in bankruptcy.

Applying the framework to EverQuest, a massively multiplayer online role-playing game, Juul concludes that the game is fundamentally an emergent system built on Dungeons & Dragons-style rules, with embedded progression structures in its quest system. Group play and cooperation arise from the emergent rules, while social and narrative texture is delivered through scripted quests. The paper closes by suggesting a practical test: progression games have walkthroughs, while emergence games have strategy guides. It positions emergence as a third path between total designer control and total player freedom.