In a mass casualty incident, injured and at-risk patients will pass through a continuum of care from many different providers acting as a team in a clinical environment. As presented at MMVR 14 [Kaufman, et al 2006], formative evaluations have shown that simulation practice is nearly as good as, and in some cases better than, live exercises for stimulating learners to integrate their procedural knowledge in new circumstances through experiential practice. However, to date, multiplayer game technologies have given limited physiological fidelity to their characters, thus limiting the realism and complexity of the scenarios that can be practiced by medical professionals. This paper describes the status of a follow-on program to merge medical and gaming technologies so that computer generated, but human-controlled, avatars used in a simulated, mass casualty training environment will exhibit realistic life signs. This advance introduces a new level of medical fidelity to simulated mass casualty scenarios that can represent thousands of injuries. The program is identifying the critical instructional challenges and related system engineering issues associated with the incorporation of multiple state-of-the-art physiological models into the computer generated synthetic representation of patients. The work is a collaboration between Forterra Systems and the SUMMIT group of Stanford University Medical School, and is sponsored by the US Army Medical Command's Telemedicine and Advanced Technologies Research Center (TATRC).