OPAL is a high-level interface for low-level physics engines used in games, robotics simulations, and other 3D applications. Features a simple C++ API, intuitive objects (e.g. Solids, Joints, Motors, Sensors), and XML-based file storage for complex objects.
The latest version of OPAL is 0.4.0. On June 23, 2010, OPAL development officially ended.