The key difference between our world and the setting of wow that's a lot of stars is the existence of the metadimension. This higher-order continuum exists alongside our liveable dimension. Energy from the metadimension bleeds into liveable world, and with proper precautions, matter can be sent through metadimensional space.
Metadimensional pathways don't align with real-world distances. They can allow a ship to cross the galaxy in days, but may keep a stellar neighbor impossibly far away.
Pathways are dangerous to uncover and can shift over time. Industries of explorers seek new and better pathways, to the chagrin of mapmakers who'd prefer if things stayed the same.
Some people develop the ability to channel metadimensional energy through their minds. Initially considered a fatal disease, it can cause brain damage, death, and even worse fates.
If controlled and used carefully, however, it can allow for superhuman feats like reading minds, seeing the future, and flight. Today, this ability is called psionics.
Most habited planets are alike in their day/night cycles, temperature range, and variety of biomes, but there are exceptions. Xeros is orbitally-locked with its star, and all civilization on it resides on the dark half bathed in perpetual night. Torm has no solid ground above sea level, and cities exist on the backs of massive sea creatures. Talmar is significantly colder than other planets in the sector, and Kuwei's toxic atmosphere necessitates biodomes for habitation.
The sector map displays metadimensional closeness of planets for transit purposes. While maps of actual location do exist, they're rarely used except by those in relevant fields of study.
Traversable stellar systems Key planetary locations Metadimensional distance
This custom setting by Rin Garnett is based on and used with the Stars Without Number (Revised) TTRPG by Kevin Crawford (check out the free and full versions at Drive-Thru RPG). All page covers use art from the official art pack. Unless otherwise noted, all other art is by Rin using public domain assets.