In this paper, we propose a new approach to developing advanced simulation environments for use in performing human-subject experiments. We call this approach the mission-based scenario. The mission-based scenario aims to: 1) Situate experiments within a realistic mission context; 2) Incorporate tasks, task loadings, and environmental interactions that are consistent with the mission’s operational context; and 3) Permit multiple sequences of actions/tasks to complete mission objectives. This approach will move us beyond more traditional, tightly-scripted experimental scenarios, and will employ concepts from interactive narrative as well as nonlinear game play approaches to video game design to enhance the richness and realism of Soldier-task-environment interactions. In this paper, we will detail the rationale for adopting such an approach and present a discussion of significant concepts that have guided a proof-of-concept test program of the mission-based scenario, which we intend to integrate into ongoing S&T research efforts.