A server for administering an on-line virtual environment comprises a data communication arrangement and a processor. The data communication arrangement receives a signal from a first entertainment device in communication with an instance of the virtual environment. The signal indicates that a user of that device has performed a predetermined action. The processor determines the availability of a second entertainment device, and is operable to switch the second device from a second instance of the virtual environment to the first instance of the virtual environment. The data communication arrangement is operable, if the second device is available, to transmit a signal to the first device indicating that a software controlled avatar within that instance should change modes to represent a user of the second device. The processor is operable to transfer control of a previously software controlled avatar within that instance of the virtual environment to the second device.