A star system of three planets:

Muur'Kari is a realm of massive tube-like caves dotted with occasional Light Islands where life can flourish. Home to the Solon, a race of tentacle-amphibians who are obsessed with being Proper and Polite.

Tle is an earth-like planet. Home to humans, then eventually Dryads when humans accidentally wipe themselves out. Has a number of relatively weak magic systems and a set of gods who compete with each other for followers in an elaborate game. Beneath the surface is The Vault, a vast zoo for extinct animals, including a long-lost race of owl-people.

Netarin is a gas giant with 4 habitable moons. They are home to the Tripods - a primitive race driven by a competition for space.