A key military priority is building resilience to stress, because of the near- and long-term effects of stress on mission performance, personal well-being, and relationships. Most stress treatment and prevention research focuses on the adverse effects of stress, neglecting to build on its potential positive effects on performance. The efforts discussed in this paper demonstrate that a software training app can provide an effective individualized method for mitigating the negative effects of stress while emphasizing its positive effects on performance. The Stress Resilience Training System (SRTS) iPad app blends cognitive training with advanced biofeedback to teach individuals to understand, regulate and exploit their stress responses, using a game-based learning framework. SRTS provides information on stress and its effects, techniques for self-regulation based on heart rate variability (HRV) biofeedback, HRVcontrolled simulations, narrative self-tests, and adaptive coaching. The paper describes the SRTS methodology and positive results from multiple evaluations, including usability and efficacy studies on military, para-military and non-military samples. The usability study showed the app is intuitive and easy to use. The efficacy studies showed that participants improved in a number of key resilience-related measures including perceived PTSD symptoms, stress and depression, and also reported improvements in on-the-job performance, personal, and familial relations. The empirical results strongly support the ability of game/simulation-based biofeedback training to build stress resilience in a variety of different populations. Evaluation results suggest additional enhancements to the methodology including: a web-based version for multi-platform delivery; increased use of biometric data for better feedback of progress; incorporation of social networking for supportive interaction; and virtual mentoring to replicate the benefits of personal mentoring. The enhancements will make the capability a more valuable addition to initial and sustainment resilience training over a range of military and non-military applications.