The dungeon is the easy part. Building a text adventure game engine taught me the hard half is teaching the machine to listen to what players actually say.
The hard part of a nine-book series is not writing nine books. It is making book seven remember what book two promised. Here is how I keep mine from collapsing.
A reference page for readers who keep notebooks. The Progenitor era through the Long Peace and the Stewardship — every major date, every Wurm Lord seal, every city, located on the heptagonal lattice that holds the continent together.