From the release:
This book contains descriptions of 50 different specific places that can be used either individually or in conjunction with one another, and within the context of the city of Kos as presented here or as part of any other community a storyteller might have established within their own campaign setting. It also includes several images by fantasy artist Amanda Kahl and a fully-keyed map of the city of Kos by artist William T. Thrasher, both in the book and as a separate 11 x 17 file that can be printed out on a single sheet of paper.
The Swords of Kos Fantasy Campaign Setting has deliberately been designed to be system free, not tied to any particular game setting, and to be compatible with any set of role-playing game rules suitable for ancient, medieval, or fantasy venues. In that the setting was used as the playtest backdrop for games using the OGL/d20, Pathfinder, “Basic” Dungeons & Dragons and Labyrinth Lord retroclone, and Advanced Dungeons & Dragons rules, of course, it is an especially ideal setting for them.