From the publisher's website:

Twilight Imperium is an epic board game of galactic conquest for three to six players. Each player takes command of one of ten unique civilizations to compete for interstellar supremacy through warfare, trade, uncertain allegiances, and political dominance. Each civilization provides a unique game experience with different abilities and play styles. Will you play as the Emirates of Hacan and preside over every trade agreement made in the galaxy, or will you be the Federation of Sol and rapidly take over worlds in hopes of dominating the entire galaxy? In Twilight Imperium many paths lead to the center of the galaxy, but every path is forged from broken promises. As the prominent leader of your civilization, you must make enemies and allies with the other respected leaders that sit around you. Alliances can be made and broken in an instant. War can be waged, and then rescinded in the matter of minutes. The galaxy isn't stable, so how you will be the beacon to guide your people through? Turn after turn, you must decide what is in your peoples best interest. Choosing a political path may allow you to use your votes which you've accumulated in passing a bill on Mecatol Rex. But what will you do next turn when your defenses are broken and your homeworld is invaded? Or, will you stage an all-out fleet assault on a bordering colony? These are all just examples of the tough decisions you'll have to make in Twilight Imperium.