Immersive Fictions: Modern Narrative, New Media, Mixed Reality presents an approach to narrative fiction that responds to the expanded role of virtual environments in contemporary life. Despite the growing number of daily activities mediated by digital technologies, the virtual is still widely characterized as the opposite of the real. The pervasiveness of this perspective is demonstrated in the frequent use of immersion metaphors to describe virtual environments. I argue that this practice perpetuates an ontological binary that obscures the ways in which the virtual enters and participates in a wired culture. Immersive Fictions reimagines the relationship between media and its users in this context in order to trace the circuits of interaction running across the supposed boundary between the virtual and real. Because the expectation that media-generated environments be "immersive" proceeds from the long tradition of describing a reader's experience of being "lost in a book," this dissertation takes the form of a comparative study of videogames and print literature and relies on an interdisciplinary approach combining new media studies and literary criticism. I demonstrate how print works such as Truman Capote's In Cold Blood and Mark Danielewski's House of Leaves and videogames such as Ubisoft's Prince of Persia: Sands of Time, Silicon Knight's Eternal Darkness, CyberConnect2's .hack//Infection position their audience not as vicarious visitors to non-actual worlds, but as book readers or game players. Their embodied engagement then becomes itself a site of the fiction as the conflicts animating these narratives are shown to be active in the material task and cultural significance of reading and play. As a result, I argue for a new understanding of "realism," exemplified by Infinity Ward's Modern Warfare series and Danny Ledonne's Super Columbine Massacre RPG!, which addresses the virtualities of fiction, not in terms of their representational or even immersive capacities, but with regard to how they situate their audience in the context of the social, political, and ethical forces bearing on their interactions with the virtual.