The Broken Shard Cluster
Demarunk - System A
Despite appearances, this system got off lucky. Legend has it that the world now called Demarunk was once a paradise, more beautiful even than Lost Earth. Certainly it was once far more pleasant than it is; the remnants of cities dot the surface, glittering and lifeless. Now the barren remnant orbits a dimming sun, and the one thing its inhabitants agree on is that the Collapse will not happen again. Dozens of different Houses maintain their own patches of viable life on the airless world, some buried deep, others in domes, a few (considered crazy even by other Demarunk inhabitants) use forcefields to hold in a local atmosphere. There are few constants amongst them - all are ruled by Engineer-Scientists, all are protective of their science, and all trade beautiful one of a kind wonders of technology. And all of them, or at least most, feel an obligation to keep other worlds from collapsing. They remember the death of billions, and won't let others repeat their ancestors' mistakes. To this end, they only trade 'safe' technology and keep their secrets hidden from those who wouldn't understand. And they are perfectly happy to meddle in other world's affairs to stop their technology from going too far, too fast. It's probably a good thing for the cluster that the population is low and the Houses don't cooperate well even on shared goals.
All evidence points to the fact that the cluster today is but a broken fragment of a much larger and more complex network of interstellar slipknots that might date back to Old Earth itself. Something happened to shatter that network, leaving this simpler, broken branch--and presumably other isolated branches around the galaxy or beyond. But evidence indicates that our current cluster could collapse even further to a simpler configuration if certain energies were applied. The application of these energies may have been what caused the collapse of Demarunk civilization. It is suspected by many Houses of Demarunk that the destruction of their world was due to an attempt to reconnect the local slipknots to other isolated clusters in the galaxy. This collapse may have weakened the local slipknot network, and the Demarunk Engineer-scientists are trying to research what went wrong so it doesn't happen again. Problem is that other factions in the cluster would like to get their hands on this lost technology to try to successfully do what the long-ago Demarunk natives failed to do. Just think of the business opportunities with new markets to exploit! But they may risk damaging the slipknot clusters even more if they do.
Qing - System B
T -1 (Atomic power) Qing has advanced information technology, but lags elsewhere.
As a world rich with resources, but where the natives have not yet achieved anything but the most primitive space travel, Qing has been carved up into spheres of influence by the major powers of the cluster, in a situation reminiscent of China in the late 19th century C.E. on Earth That Was. There are a number of major polities, with various forms of government, ranging from democracy to autocracy. All of them remain formally politically independent. In practice, most are dominated by some power from outside the system, seeking to exploit the world for its rich resources. Representatives of these foreign powers have immunity from local law enforcement and will often use their own troops to enforce their will alongside the local police and military, always under the fiction of helping the local government maintain order. Members of Qing's upper classes may receive an off-world education in one of the colonial powers' universities. This colonialism has not gone unchallenged, with many different anti-colonial movements active, with a range of philosophies from religious fundamentalism to democratic socialism, and a range of methods from terrorism to nonviolent protest.
One distinct aspect of Qing's history of which its people are proud is that they have not fought conventional open wars. Instead, they have fought what are known as shadow wars, relying on methods ranging from propaganda and psy ops to assassination. The people of Qing see this as superior to the open warfare seen elsewhere in human history, as this rarely results in civilian casualties, only involving those actually wielding power. Some of the outside powers have recruited Qing psy ops specialists and assassins to work for them in the rest of the cluster. Even the nonviolent anti-colonial movements make as much use of psy ops as they do of open, mass protest.
Werve - the miracle drug. Probably not naturally occurring, it's just too useful. If it's engineered, though, its creators are long gone. The plant itself is rare, near impossible to farm, while it will grow on other worlds or in controlled environments, it won't produce the compound everyone loves it for. ingesting even small amounts of werve regularly slows aging, fights cancer, and induces a mild euphoria that doesn't get in the way of your work while being very pleasant. Qing has many resources to export, but werve is probably the most valuable, and conflicts between polities can result from finding a rich patch of the plant.
Yebon Domes - System C
T -2 (Industrialization)
The system in which Yebon Domes resides was long considered useless by and large, until an innovative soul in the interstellar corporation Trellen Industries came up with an excellent idea for it several decades ago. The Yebon Domes have now become the premiere prison planet for the cluster. Each Dome is essentially a shell that provides air for its inmates, with some shipments of food, water, and raw materials for them. Mostly on the later, because it's far more efficient and good for security if the prisoners are constantly busy taking care of their own survival.
While most of the prisoners in the Yebon Domes are common criminals or leaders of organized crime groups, a sizable number are political prisoners. Leaving political prisoners largely unsupervised has turned out to be a bad idea (at least from the perspective of the people imprisoning them), since they have taken the opportunities presented by the Yebon Domes to politically educate and organize the prisoners. While in some domes, their efforts have been stymied by the leaders of criminal gangs, in others they have begun to be successful. These political prisoners and "ordinary" prisoners who have become politicized are now trying to build ties between the domes. The efforts to do this are slowed by the wide range of political ideologies and differing ideas about strategy (from terrorism to nonviolence) present, but they are slowly building links. And the powers-that-be remain largely oblivious to all of this, confident that their system is fool-proof.