A display apparatus for displaying a moving object traversing a virtual display region, the apparatus comprising: a group of two or more networked client computer devices (10, 20, 30, 40, 50) each being configured to display a respective portion of the virtual display region, in which each respective portion is defined by a set of edges, each edge being classified as a hard edge (140, 160), from which the moving object is reflected, or a soft edge (150, 170) through which the moving object is allowed to pass; and a path controller, associated with each client computer device, for defining a path of the moving object with respect to the portion of the virtual display region which is displayed by that client computer device; the path controller being configured, when the path controller defines a path which intersects a soft edge of that client computer device's portion of the virtual display region, to transmit path data defining the path of the moving object for use at least by another client computer device which displays the next portion of the virtual display region which will lie within the detected path of the moving object; the display apparatus characterized in that for each client computer device, a predetermined period lies between successive occurrences of that client computer device receiving path data; at least one of the client computer devices comprises a user control which, when operated by a user while the moving object is currently displayed by that client computer device, is operable to cause that client computer device to alter one or more of the rendered appearance, the position, the speed and the direction of motion of the moving object; when the user control is operated to change the speed or direction of motion of the moving object, the client computer device is operable to apply a delay period before fully implementing the required change in speed or direction; and the delay period before fully implementing the required change in speed or direction is greater than or equal to the predetermined period between successive occurrences of each client computer device receiving path data. a group of two or more networked client computer devices (10, 20, 30, 40, 50) each being configured to display a respective portion of the virtual display region, in which each respective portion is defined by a set of edges, each edge being classified as a hard edge (140, 160), from which the moving object is reflected, or a soft edge (150, 170) through which the moving object is allowed to pass; and a path controller, associated with each client computer device, for defining a path of the moving object with respect to the portion of the virtual display region which is displayed by that client computer device; the path controller being configured, when the path controller defines a path which intersects a soft edge of that client computer device's portion of the virtual display region, to transmit path data defining the path of the moving object for use at least by another client computer device which displays the next portion of the virtual display region which will lie within the detected path of the moving object; the display apparatus characterized in that for each client computer device, a predetermined period lies between successive occurrences of that client computer device receiving path data; at least one of the client computer devices comprises a user control which, when operated by a user while the moving object is currently displayed by that client computer device, is operable to cause that client computer device to alter one or more of the rendered appearance, the position, the speed and the direction of motion of the moving object; when the user control is operated to change the speed or direction of motion of the moving object, the client computer device is operable to apply a delay period before fully implementing the required change in speed or direction; and the delay period before fully implementing the required change in speed or direction is greater than or equal to the predetermined period between successive occurrences of each client computer device receiving path data.