Uncle Jimbo's Bug Huntin' Range
I was reading about Traveller 's Jgd-Il-Jagd , a species inhabiting gas giant worlds who are interesting for many reasons, among them their literally violent objections to the common Traveller practice of skimming fuel by a supersonic run through a gas giant's atmosphere. I wondered if Star*Drive might have some equivalent species who would object to bright flashes of light on the fringes of star systems, and soon thought of a suggestion by Gerald Feinberg and Robert Shapiro (which seems to be too old for the Web) of lifeforms in an environment so cold that no chemical processes can operate, instead existing by physics-based processes involving variable rotation of super-cold hydrogen atoms. It turns out that Larry Niven had a similar idea .
A GM could make use of the Night Lurkers at different stages of the history that I've sketched out, depending what style of campaign they intend. The first contact or early contact periods might be interesting to play out. Later, it works instead as a region of space with odd customs and conditions for scenarios that require the heroes to travel to Inside (see below).
The Night Lurkers don't allow heat-radiating sun-dwellers to approach too closely, but in long-range video, they appear as vaguely hood-shaped membranes made of something like black cobweb. In closer inspections by contact drones (more on these later) and biological data that the Shkorch have agreed to provide, they are actually fairly durable in mechanical terms - perhaps comparable to silk or nylon - and have a number of intricate limbs folded under the mantle.
As several of these references may suggest, the known Shkorchor systems (that is, the ones they have restricted) form a rough curved line starting at Keynes's Star. This is the very edge of a recent star-forming region, the Brandysnap Cluster (named for the colour of several of its stars) where it meets a dark nebula. The Rim stars are dimmer and at least half a billion years older. Astrobiologists agree that the Shkorch biosphere must be older than the Brandysnap stars and would have been profoundly affected by their ignition (the aliens themselves are hardly likely to have records of that epoch, but should have found traces early in the development of their biological sciences).
The systems further along the line of the Rim first had catalogue numbers, then designations as Rim Beta, Rim Gamma, Delta, Epsilon and so on. Now the systems open to humans have been named by their colonists: Rim Beta as Inside, Gamma as Sufferance. The watching presence of Night Lurkers very much rests at the back of everyone's mind.
For some years, the relationship between Shkorchor space and members of the Stellar Ring species, based on the first contact point at Keynes's Star, has been quite unequal in favour of the aliens, as their well-supported fleet faced down a ragged series of free traders and independent colonists. They have insisted on regulation of human movements by a rough arrangement that has become a well-founded tradition, where the Night Lurkers permit ships to pass under the pilotage of certain humans who they know and trust to make accurate starfalls into the inner systems that are of no interest to the aliens, while taking ships only as far into the Rim of Night as the Shkorch agree. The Shkorch do not state outright the consequences of refusal, though the inhabitants of the Rim, rightly or wrongly, attribute a number of disappearances of ships to their displeasure.
The cantina at Witch's Tit Station has gradually become a known point of contact between trusted local pilots (who are taking on more of the organisation of a guild) and Emissaries, in a good-sized alcove next to the entrance, unlit except for reflected glare.
Pilots and others experienced in Shkorch contact wear an e-suit comm and translator unit on a padded collar to receive the Emissaries' transmissions. The Shkorch first contacted humans through their suit transceivers and may still not grasp the concept that humans speak to each other through atmospheric vibrations rather than radio, though Shasta probably suspects we have a channel of communication that the Emissaries don't pick up.
A ship might crash land on Shkorch world. Diplomats will need to find the way to negotiate the rescue mission. Species specialists will need to help once the planetfall is made in order for the rescuers not to disturb the Shkorch.
A conflict can come as a thief/smuggler tries to sell one of the Shkorch artifacts/weapons and the aliens want it back.
One of the emissaries could end up 'dead'. Troubleshooters and negotiators need to be brought in to solve the murder and prevent racial conflict.
A Shkorch comes aboard the WT asking for asylum. He also offers to give away some of his people's artifacts for it. What drove him to such desperation to contact heat-emitters for help and what happens when other Shkorch ask for the escapee to be surrendered? How will station administrators react to the attractive offer of obtaining Shkorch tech?