Earthfall

Centuries after Earth was rendered an uninhabitable wasteland, humanity was forced from its homeworld and founded the Kepler Circuit, a string of colonies throughout the solar system. These settlements provide resources to the remnants of humankind, the most important resource being the newly discovered element—Gravitum—found only in the Earth's unstable mantle. But a powerful religious faction known as the New Earth Tribunal has risen to preside over most of the Circuit. Though there is barely a faction left to challenge them, a string of attacks on the Tribunal's freighters causes them to suspect their mortal enemies, the Ceresians, of foul play.