The philosopher and educator John Dewey (1938) supported a transactive view of schooling, where learners are active change agents rather than passive observers, and through their actions and consequences, they transform the problem into a known. Modern technologies now make his vision a reality, putting learners as active protagonists in their own learning, taking on authentic roles via avatars, and seeing the consequences of their actions played out in a 3D immersive world. The strength of this kind of game-based learning is what we call Transformational Play; a 3-fold theory that positions the person with intentionality, the content with legitimacy, and the context with consequentiality. Grounding this theory in context, we designed an educational 3D role playing game (RPG), school curriculum, and large-scale comparison study in 18 seventh-grade classrooms (N=450). This study demonstrates the positive impact of game-based learning in a compelling population of disadvantaged students (Latino, Native American, poverty), who have new access to rich technology, as part of a 1:1 laptop initiative. These students, many of whom are second-language learners, showed significant gains in literacy, persuasive writing and engagement in 2.5 weeks of gameplay in a 3D immersive narrative based on Mary Shelley's Frankenstein. In this 3D curriculum, "The Doctor's Cure", students take on the role of an investigative reporter via their avatar, and complete a series of missions to uncover a moral dilemma involving Dr. Frankenstein's work. As reporters, students actively collect evidence through interviews, build logical arguments to support their theses, submit these to an in-game logic machine for evaluation, and get feedback about the alignment between their evidence and reasoning. Additional game tools and scaffolds allow students to act 'a head above' their current literacy capabilities (Vygotsky, 1978), while teachers play and provide feedback in their game-character role as the 'Editor'. With the goal of having equally engaging and novel experiences for both conditions, the control condition used the graphic novel curriculum 'Frankenstein'. Measures of engagement (based on Csikszentmihalyi's Flow, 1996) showed both conditions rated the experiences equally engaging. Further, we designed teacher-led activities for the graphic novel to closely parallel the scaffolds in the game curriculum, and both conditions wrote and revised persuasive pieces. Despite these similarities, interesting and significant differences emerged. Students in both conditions showed significant learning gains on lowerlevel items identifying basic components of persuasive writing. However, the game-based students scored significantly greater on the higher-level task, requiring students to craft and compose their own persuasive essay from the ground up. Further differences emerged in the engagement measures and observational field notes. Qualitative analyses were used to unpack the quantitative findings, which illuminated the strength of in-game tools for creating a fluency in these literary practices. The findings support the theory of Transformational Play and its potential for the classroom; that students can be scaffolded via games to engage personally and meaningfully in complex learning, that is experientially consequential and personally transformative.