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.