Mars. Earth's first terra formed world. Independent settlements left alone by the rest of the system. To save themselves from invaders and crises, the small independent Martian factions unite into a single government, known as the United Factions, or simply UF. They are at war with a mysterious alien race, which call themselves the Sentinels. The Sentinels are inorganic, yet have organic neural structures, more complex than humans'. The Sentinels are in a civil war between a religious faction called the Followers of Light, and the larger and secular Sentinel Central Matrix.