The authors present a virtual tennis game. They describe the creation and modeling of the virtual humans and body deformations, also showing the real-time animation and rendering aspects of the avatars. They focus on the animation of the virtual tennis ball and the behavior of a synthetic, autonomous referee who judges the tennis games. The networked, collaborative, virtual environment system is described with special reference to its interfaces to driver programs. They also mention the virtual reality (VR) devices that are used to merge the interactive players into the virtual tennis environment, together with the equipment and technologies employed for this exciting experience. They conclude with remarks on personal experiences during the game and on future research topics to improve parts of the presented system