Starsiege is a mecha-style vehicle simulation game developed by Dynamix and released in 1999. Starsiege is set in the Metaltech/Earthsiege universe, which contains its predecessors Earthsiege (1994), Battledrome (1995), and Earthsiege 2 (1995), as well as action game Hunter Hunted (1996), strategy games Mission Force: Cyberstorm (1997) and Cyberstorm 2: Corporate Wars (1998), and first-person shooters Starsiege: Tribes (1998), Tribes 2 (2001), Tribes: Vengeance (2004) and Tribes: Ascend (2012). Starsiege is the end of the Earthsiege series and the beginning of the Tribes series.
In this time, humanity is nominally united in an Empire, led from Earth by the Immortal Emperor Solomon Petresun. Petresun's policy is the defence of Earth at all costs. While Earth is prosperous and well protected, the colonies on Luna, Mars, and Venus suffer from increasingly harsh regulations and production quotas.
The combat units of the Empire are represented by the Imperial Police, Terran Defense Force and the Imperial Knights. The former paramilitary group is responsible for maintaining order in the colonies. The Terran Defense Force are the standard military with bases from Mercury to Titan. The Knights, led by Grand Master Caanon Weathers, are the military's elite and are provided with the best pilots and equipment; naturally they are based on Earth. The Knights have customized versions of the standard HERCs.
The inequality between the colonies and Earth foments rebellion. In 2802 there are two guerilla movements on Mars, the Free Martian Alliance (FMA) and the Martian Liberation Front (MLF). The FMA concentrates on destroying and capturing Imperial infrastructure and supplies. The MLF focuses on killing Imperial personnel and sympathizers. Both groups operate from underground bases and make do with modified mining HERCs and tanks. The rebels partially offset their disadvantages with superior weapons taken from the alien "Tharsis Cache"; an underground stockpile of alien technology discovered by rebels while digging new tunnels. Eventually the rebellion becomes too great for the police to contain and the Knights are deployed to Mars to crush the insurrection.
Notable Cybrid units include the elite Platinum Guard - those closest to Prometheus - and the heretical Metagen. The former have access to customized HERC designs. During the Cybrid campaign, the player is ordered to destroy Metagen units. They are little mentioned in the human campaign; in the final mission Cybrids supposedly guarding Prometheus abandon their posts and refuse to fire on humans for "unknown reasons."