Set on the red planet not as it exists, but as people at the turn of the 20th century thought it might be, Shadows of a Dying World is drawn from the Mars series of Edgar Rice Burroughs and presents creatures from his world in game terms. Its contents are compatible with any games that use the OGL system and can be inserted into them in whole or in part. On this Mars, elegant city-states rise along the banks of world-spanning canals, luxurious airships ply the thin atmosphere, feisty princesses and feckless nobles are menaced by killers of the drear dried-up sea-beds, and skilled swordsmen defend dynasties that have ruled for aeons. Despite both wondrous technology and mysterious mental abilities developed beyond the comprehension of Earthlings, however, the most farsighted of the Martians know that the history of their world is drawing toward its end, and that its life-giving atmosphere and waterways are already sustained only by vast efforts of engineering. Shadows of a Dying World presents the unique wonders and dangers posed by the weirdly sentient denizens of Burroughs' Mars. Creatures covered in Shadows of a Dying World include the Apt, Banth, Calot, Corphal, Great White Ape, Green Martian, Kaldane, Rykor, Plant Man, Silian, Sith, Thoat, Ulsio, and Zitidar. Other features of this book include guidelines for using Burroughs' creatures in both Mars and non-Mars campaign settings, Martian random encounter tables, new Feats, the Class Defense Bonus combat option, and original illustrations by artists Brendan Cass, Sharon Daugherty, William Hazzard II, Amanda Kahl and Geoff Weber. This book also comes with Combined Creature Creation, a 52-page bonus document compiled and used during the creation of this book and provided as a useful tool for game masters.