A passive prop for controlling the operation of a video game through visually detecting and tracking the prop. One aspect of the invention is a spherical prop of principally one color, but with a spot of another color located on the sphere. This provides control of a video system through tracking of position and orientation of the prop. Another aspect of the invention is a planar offset prop consisting of two color regions, a first color region being offset from a second color region. A third aspect of the invention allows the provision of a push-button control for a simple, passive prop, the push-button being effective to cause a color region of a prop to change color.