Master of Orion III (MoO3, MoOIII) is a 4X turn-based strategy game and the third in the Master of Orion series. MoO3 was developed by Quicksilver Software and published by Infogrames on February 25, 2003.
In The Master of Orion III game manual, the player discovers that the planet called Antares in Master of Orion II was actually a forward base, "ConJenn". Following the events of Master of Orion II, the Antarans retaliated and defeated the young races of the Orion Sector, enslaving all of the people on every planet, and destroying all research and military centers, effectively making any retaliation impossible.
A thousand years later, the Antarans mysteriously disappeared due to an outbreak of their "Harvester" bioweapons program, which wiped out 98% of the population living in the Antaran sector. Survivors were left primarily on only two planets: Antares itself, and the Antarans living on the planet Orion, ruling the Orion Sector from Master of Orion II. Other Antarans survived in various smaller colonies and outposts throughout the galaxy.
The Antarans on Orion overseeing the younger races from Master of Orion II concluded that without backup from their powerful empire, changes would be necessary. Anticipating rebellion, they arrogantly declared themselves the "New Orions" (as opposed to the true ancient ones), and allowed a new Senate to be convened, made up of younger races. Half a dozen races from the previous games launched a rebellion, but were beaten into near extinction (isolated colonies and refuges of these races would remain throughout the sector). Rumors would also abound of a legitimate heir to the Orion throne.
Meanwhile, a group of isolated Antarans engineered a new bioweapon known as "Harvester Zeta". One of their scientists brought a shipment of these sentient parasites to the Orion sector, where they were released upon on a Human outpost, wreaking terrible damage. However, being sentient, the Harvesters began to pursue their own agenda, spreading and forming colonies like other races, and giving themselves a new name, the "Ithkul".