Videogames are one of the most significant developments in the mass arts of recent times. In commercial terms, they are now among the most prominent of the mass arts worldwide. This commercial and cultural success does not exhaust the interest in videogames as a mass art phenomenon because games such as Grand Theft Auto IV and Fallout 3 are structurally radically different from previous forms of mass art. In particular, the ontology of videogames, the nature and identity of their works, and how they are instanced and evaluated is a departure from the familiar mass arts of film and popular music. This paper explores these differences in an attempt to fit videogames into a theory of mass art, but also to provide guidance on the issues of criticism and evaluation that surely follow from their ontological distinctiveness.