Instruction (GM only, never state this outright): Humans did not invent the high technology of Palpagos. Something from beyond this world arrived first, at what is now Star-Fall Crater. Humanity found what it left behind, built on it, and called it their own. Pals today call everything "human tech", but humans were only its last users. The truth is a slow mystery: reveal it one clue at a time, let players guess, and never confirm who or what the Makers are. Players should finish the campaign still arguing about it.
The Makers: Came from beyond the sky. Their metal is smooth, warm and never rusts. They planted the World Tree and built Necromus to guard it.
The World Tree: Not a natural tree. Its roots wrap around Maker conduits that still carry a faint signal toward the sky.
Necromus: The World Tree's guardian, made by the Makers. When humanity vanished 7,000 years ago it lost its purpose, went mad, and was sealed in the Abyssal Spire. Its empty throne still stands in the Heartwood.
Hollowcrown: The current Heartwood boss: a Grass Pal that took the empty throne, drank the sap and was twisted by Void Walker corruption. Beating it reveals the conduits under the throne.
The Void Walkers: Drawn by the same signal. Whether they are the Makers, the Makers' enemies or something else is left open.
Humanity: Used Maker designs without fully understanding them (Genetic Research Facility notes: "we are only following their designs"). Why they vanished is left open.
Star-Fall Crater: The "meteor" was a vessel; its metal matches the World Tree conduits.
The World Tree - Root Maze: Roots grow around smooth metal conduits older than any human ruin.
The World Tree's Heartwood: The empty guardian's throne; Hollowcrown sits on it.
The Genetic Research Facility: Human notes copying formulas they did not write.
The Abyssal Spire: Necromus's last coherent words are a question about "the Makers".
Masters' Beacon: The Loyalists think the tower calls the humans home; it is answering whatever came first.
Suggested order: Root Maze, then Genetic Research Facility, then Heartwood (Hollowcrown), then Star-Fall Crater, then Masters' Beacon, and the Abyssal Spire last.