Moonfire (2003)

From Introduction:

Welcome to Moonfire, the first d20 System campaign booster from Thousandpress. Campaign boosters are designed to preserve the time, effort, and creative energy that many of you have invested in your campaigns. You have created many pages of location notes, detailed culture descriptions, timelines, hand drawn maps, curiously eccentric NPCs, and mysterious cults. No GM should give that up. Players too have treasured NPC relationships, great cliffhanger stories, and scores of treasures, wounds, and quirks that all depend on the campaign. They would like to play there forever. And yet something is not right. Favorite cities are a bit too familiar. All the royal heirs have been rescued at least once. Once dangerous wilderness has too often heard the pitter patter of PC feet. The last dragon they slew was the scourge of the land… where was the next one hiding all this time?

Enter Moonfire. Moonfire gives gamemasters a few unique twists on the implementation of their existing rules base. It also supplies a cosmological template that justifies the differences between your swords and sorcery campaign and the mundane world. Finally it has the capacity to change everything about how you play without destroying campaign continuity, burying you in new rules, or worst of all, forcing you to start from scratch. Just read on and add dice. The rest takes care of itself.