In the center of the circular game board is a planet. A grid is made of concentric circles around the planet intersected by straight lines radiating from the center. The grid is in turn subdivided into three major layers separated by thicker concentric lines representing an asteroid barrier, a magnetic field, radiation belt. One player protects the planet from others intent on stealing its energy resources. The board has two halves that fit together jigsaw-style. Note: There are separate game pages for the 1975 card game from Whitman and the 1976 board game from Milton Bradley, as well as the Italian game Spazio: 1999.