DOI: 10.1145/1077246.1077258In this article we attempt to describe and analyze the formalisms of pervasive games and pervasive gaming (PG). As the title indicates, PG consists of atomic entities that nevertheless merge into a molecular structure that exhibits emergent features during the actual game-play. The article introduces four axes of PG (mobility, distribution, persistence, and transmediality). Further, it describes and analyses three key units of PG (rules, entities, and mechanics) as well as discusses the role of space in PG by differentiating between tangible space, information-embedded space, and accessibility space. The article is generally concerned with classifying the indispensable components of pervasive games and, in addition, it lists the invariant features of pervasive game-play, meaning the epistemology that is tied to this new kind of gaming situated on the borderline between corporeal and immaterial space. Of particular interest are game rules in pervasive gaming, since they seem to touch upon both the underlying, formal structure of the game (i.e., the ontology of PG) and the actual play vis-à-vis physical and/or virtual constraints (i.e., the PG epistemology).