For many years, the galaxy was a peaceful place. After the relentless war between Terrans and the Hegemony, all major spacefaring species made significant efforts to prevent such events from happening again. Nevertheless, tensions are rising among the seven major species and within the Galactic Council. A confrontation seems inevitable.

In Eclipse, players become the leaders of vast, interstellar civilizations and compete against their rivals in eight rounds for dominance over the galaxy. In each round, players expand their civilization by exploring and colonizing new space sectors, researching technologies, and building up their space fleet. After the eighth round, the winner is determined by who has accumulated the most points through won battles, diplomatic alliances, control over sectors and monoliths, discoveries, and technological achievements.