Mars is not a large planet, merely half the size of Earth, yet it hosts several native habitats and tens of thousands of native species. The noted, and sadly late, Dr. Arthur Wesley has explored many of these and filed extensive reports with the International Committee on Intellectual Cooperation. This publication details the most extensively studied creatures of Mars, their native habitats, and includes drawings based on the sketches of Dr. Wesley himself with an appendix on artificial life on Mars written by Frank Knight.

Over 20 new creatures native to Mars such as the crested mahmoot, giant tesselon, and enigmatic vapor wraith are fully statted out with story hooks to help the GM get them off the page and into the game. Major ecosystems of Mars such as the rice grass savanna of the South Polar Region, the lush (for Mars) canal valleys, and the dangers of the open desert are detailed. In addition, Frank Knight has appended his thoughts on the artificial life on Mars, such as warbots and the dread roboqueen!