An element of video games often attributed to their cultural, economic, and social dominance as a media entertainment form is their interactive nature. Broadly, games actively engage the player in the on-screen actions of their digital worlds. Scholars have focused on this interactivity as a core variable to understand a variety of gaming uses and effects, but conceptualizations of the construct vary and are often non-specific. To this end, the opening chapter recasts the underpinnings of this interactivity from the perspective of the human-computer dialog exemplified by video game play. As players engage games, the player and machine together co-create the cognitive, emotional, physical, and social dimensions of the gaming experience.