Hybrid Client-Server Graphical Content Delivery

A hybrid client-server multimedia content delivery system 100 is provided for delivering graphical information across a network 30 from a server to a client device 200. An initial set of object data 350 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 210. 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. The server further comprises an asset library which stores the object data; a data management unit which transmits the object data from the library to the client device; and an environmental engine which monitors a virtual environment being presented to the client.