The eXtensible Dynamics Engine (XDE) is a high-performance real-time simulation platform developed by the CEA for precise teleoperation in nuclear fusion reactors. Combining a rapid physical simulation engine with ROS protocols, XDE enables responsive robotic manipulation, enhanced by Extended Reality (XR) for augmented visualization and real-time data overlays. These features improve situational awareness and reduce operator cognitive load. With its modular architecture, XDE is advancing toward physical validation, positioning itself as a powerful solution for nuclear decommissioning and other high-risk applications.