Sirian is a space-age sci-fi setting that tries to adhere to more science than fiction in terms of technology and space travel.
The nations of Sirian are broken into two clusters: the northern Rohearn and San-saram and the Southern Coalition of Dalhan, Gargorian Colonists and Clanspeople. The Rohearn lived in neighboring militaristic republics that warred with each other and sought expansion in the south, leading to a long period of war between the hemispheres, with the Northern Republics frequently ending up on top.
Most RP centers around a series of orbital space stations, the most popular of which is Station Prime under control of the Treatise Body, an alliance of northern and southern nations. Other major players in orbit are The Independents of New Domai and the organized crime of Shrapnel City
A recent catastrophe called The Inferno left the planet practically a wasteland. All psionically-active persons began falling victim to an affliction that, over time, robbed them of their free will and turned them into cold, calculating killing machines called "The Crowned." Hordes of Zombies called Unlife often follow with them like drones to a hive queen.
Prior to the Inferno, the Southern Coalition unearthed two pieces of ancient Sirian technology: a pair of starships called the Kalvania and Extravia capable of faster-than-light travel. Curious about the galaxy around them, a contingent of southerners (with some northern deserters) embarked on a multi-year, intergalactic voyage that included first contact with several alien species.
Among those encountered were the hostile Mutaren the Juren empire whose forebears colonized Sirian Planet ages ago, the ConFabs (sentient nanomachine clusters) of the Taramar station, and the Gargorian homeworld.
The Fleet returned roughly six months after the Inferno, surprised to discover the world they left was now practically a wasteland. Regular rescue missions now bring more refugees and supplies into orbit where the Treatise Body, a joint Northern/Southern governing body, tries to provide security and quality of life to the survivors in space.
For a more detailed timeline go here: Sirian History For a list of sessions go here: Sirian/Sessions and Sagas