Abstract: A hybrid client-server multimedia content delivery system is provided for delivering graphical information across a network from a server to a client device. An initial set of object data is provided sufficient for the client device to begin representing the virtual environment, followed by one or more subsequent items of the object data dynamically while the client device represents the virtual environment on the visual display device. The server maintains shadow rendering information identifying the items of object data which are currently in use at the client device. Delivery of subsequent object data to the client device is ordered and prioritised with reference to the shadow rendering information.