A rotational game decorative device is disclosed, including: a aquatic lamp main body, a magnet-driven element, a buoy and a bottom base. The magnetic-driven element and the buoy are disposed inside the aquatic lamp main body. The top and the bottom of the buoy are disposed with a plurality of rotational plates disposed with interval. The bottom base is fixedly engaged to the aquatic lamp main body with a magnetic rotational axis for correspondingly attaching to the magnet-driven element, and driven by a driving element to rotate. When the magnetic rotational axis rotates, the magnet-driven element also rotates because of attachment to the magnetic rotational axis so as to wave the fluid inside the aquatic lamp main body, which leading to pushing to rotational plats to rotate the buoy.