As adolescents face increasing academic, familial, and social pressures, their stress levels rise, leading to persistent emotional distress and loss of interest in activities. This issue is exacerbated by immature psychological development and poor self-regulation, resulting in higher rates of hospitalizations and dropouts. Traditional stress management interventions, such as therapist-guided techniques, often lack engagement and fail to capture the interest of adolescents. This study introduces Soul Gate, a serious game designed for adolescents aged 11–17, which integrates biofeedback technology and Self-Efficacy Theory. Utilizing the Experience, Dynamics, and Artifacts (EDA) game design framework, the game incorporates engaging mechanics and is structured around Cognitive Behavioral Stress Management (CBSM), featuring four key stages: breathing exercises, heart rate training, attention bias training, and heart rate variability regulation. By leveraging these principles, it offers an interactive self-help tool to enhance stress regulation and emotional resilience. Soul Gate employs a dual-system biofeedback approach, monitoring physiological indicators such as heart rate and brainwaves, and providing real-time adaptive feedback in games that improves player awareness and emotional management. A randomized controlled trial will assess its effectiveness, with expected outcomes demonstrating its potential as a viable intervention for reducing adolescent stress and enhancing emotional self-regulation. This study highlights the value of integrating biofeedback with gamification in mental health therapy and outlines future research directions to improve cultural adaptability and device portability.