A planet-wide epidemic caused by an extraterrestrial virus totally changed all women of the planet of Velian. Their bodies transformed to become parts of collective intelligence, presumably controlled by some non-humanoid creatures. The Velian men proved to be resistant to the virus, but they lost their status of free intelligent beings and only existed as suppliers of biomaterial for further gene experimentation and as parts of complex biomechanical systems. The society became now a kind of matriarchal hive.
The Galactic Federation lost several dozens of transports due to enemy attacks in the second half of the 24th century. A deep analysis of the situation made it clear that the aggressor comes from the Velian star system. It is there that the Federation is sending an expeditionary corps to destroy the hostile civilization that threatens the very existence of the human race and to investigate the fate of the missing colonists.
You are a trooper of the government army sent with the expeditionary force to attack Velian. As you accomplish missions given to you at the headquarters, you get new opportunities in selection of weapons and military equipment. Each mission will also get you closer to the secret of the origin of the Velian anomaly of the human race.
source: www.madia.ru/matriarchy.html