It's a strategy game set in space, of course. You are the leader of the human race just after the invention of "Hyperspace," which allows ships to go to distant stars relatively quickly. Eventually, you encounter other races that inhabit the universe. The object of the game is either to destroy all other races, transcend life as physical matter (basically, a scientific victory), dominate 66% of the galaxy, or form an alliance with every civ (a diplomatic victory).