1. An entertainment device for receiving images from a video camera, the device comprising: a combiner operable to combine images captured by the camera with a computer-generated image of an object resting on a virtual surface so as to generate a composite image; a detector operable to detect image movement in the captured images in one or more contact point regions corresponding to image positions at which the object contacts the virtual surface; and an initiator operable to initiate movement of the object to a new position with respect to the virtual surface in response to detected motion in the contact point regions of the captured images, in which: the detector is operable to detect whether a first image area corresponding to a captured image feature is greater than a predetermined proportion of a second image area corresponding to a full field of view of the camera; and in response to a detection that the first image area is greater than the predetermined proportion of the second image area, the initiator is operable to initiate movement of the object to an avoidance position within the composite image; wherein the avoidance position is a forward image position corresponding to a lower edge of the captured images.