Periodic maintenance of freight trains is essential for ensuring the safety and reliability of railway transportation systems. However, these complex operations require specialized technical skills and substantial hands-on experience. Maintenance technicians identify anomalies, defects, or potential damage to rail vehicles and execute timely interventions. Their tasks are further complicated by challenging working environments, such as noisy and crowded rail yards, where strict adherence to safety protocols and procedural accuracy is crucial. This paper presents the design and current development status of an immersive Virtual Reality (iVR) serious game aimed at enhancing the maintenance training of freight train technicians. The proposed system is designed to offer personalized and adaptive training, real-time task guidance, and continuous operational support for maintenance personnel. By simulating realistic maintenance scenarios, we hypothesize that iVR environments can significantly improve procedural understanding and safety compliance. We aim to deliver an adaptive, interactive, context-specific training framework grounded in principles of Human-Centred Design (HCD). Preliminary system implementation is complete, and validation with domain experts is scheduled.