The case study research reported in this paper followed the iterative design trajectory of youth game designers (ages 11-17) in a week-long summer game design camp, focused on the fundamentals of video game design. Drawing on data from a daily conceptual pitch and feedback activity, the research team traced the iterative design trajectory for one team, providing a detailed case study. Findings detail two major iterations within their week-long design trajectory following their shift from initial concepts to interacting systems and their increased focus on player experience. These trajectories were analyzed in relation to a learning environment design framework that informed the camp, explicating the ways these youth game designers engaged in practices, thinking, and dispositions important to game design.