In this dissertation I propose a reimagining of two of the central pleasures of digital media: Agency and Transformation. The first of these pleasures – Agency ¬– is a concept that has received significant attention in the discourse around games and storytelling. The second pleasure – Transformation – has received comparatively little deep investigation. In this work I will first undertake to map the territory of the discourse surrounding these two central concepts, returning first to the foundational work of Janet Murray (Murray, 1997), and then expanding my discussion to incorporate a wide range of theoretical perspectives from the different disciplines surrounding game studies. I argue that agency has been systematically misconstrued within the digital games and interactive digital storytelling communities in ways that overlook the core pleasure of agentic action within a narrative. To reframe agency, I draw on theories of communication and speech act theory to build a new understanding of how the pleasures of agency operate within a participatory narrative. This new approach to agency illuminates the ways in which the pleasures of enacting narratively meaningful moments in a game are equal to or greater than the pleasures of unrestricted action in a simulated world. I then turn my attention to transformation. I argue that understanding the pleasures of transformation can profoundly alter how we imagine, analyse, and design digital narratives. In order to build a robust theory of transformation, I turn to a field of study where identity transformation is a central concern: the dramatic arts. Drawing heavily on theories from Method acting, I identify a core poetics of transformation for digital stories. This new understanding of transformation highlights the importance of external frameworks of meaning (such as narrative scripts, rules, and goals) in guiding and supporting the enactments of a player in a story. I ground these two theoretical lenses in a close reading of the Mass Effect trilogy of story based games, from which I derive a framework of design poetics for digital narrative.