All of the so called Homeworlds reside within the Viridia-Solaris/Leviathan binary system. This is the cradle of Pan-Humanic space, the system where humans first evolved on the planet Viridia, and colonised their nearby planetary neighbours.
Viridia is the lush jungle planet where life first appeared in the system. It is home to the Viridians, who practice a form of capitalist government in which every citizen is a shareholder in the state. An individual's influence is determined by how many shares they have amassed. The primary industries are agriculture and bio-fuels.
Ironglass is a large desert planet which was originally settled to be a penal colony. Following a war of independence, it is now the home of the Ironglass Senate, a harsh military dictatorship that still utilises the brutal regime of the penal colony to supply its labour requirements. Ironglass's primary industries are mining and sand processing for ores and minerals.
Vacillus is a barren, icy planet orbiting the dead star Leviathan. It is the home of VASA, an organisation that grew from a Viridian test base for grav-shunting technology to a vast protectorate that serves as a galactic customs and police force. VASA has no industries of its own, it thrives on tolls gained from trade passing through the grav-wells.
Prime is a unique, teardrop shaped planetoid orbiting the outermost reaches of the system in a great ellipse. It is home to the secretive, isolationist Syntha, once a research colony they won independence after a war of secession. They practice a form of transhuman collectivism and believe in accelerating human evolution by merging people with machines. Their state is administered by a vast AI called Prime, and their homeworld is the only known source of the mineral Prime Obsidian, used to create AIs and human-machine interfaces.