From the release:
Crawling out from the wreckage of nuclear, biological, and chemical warzones, created in the laboratories of misguided geniuses, and spawning in realms contaminated by wild magic, mutants are both a race unto themselves and no race at all. Viewed with a mixture of contempt and pity by members of more clearly defined species, mutants are united in desperation by the abnormalities which separate them from other humanoids. As diverse — if not more so — in form and outlook as other humanoids, mutants display the best and worst characteristics evolution has to offer.
This title contains guidelines for playing the Mutant Race as characters and includes details on physical appearance, society, relations with other races, alignment and religion, and typical adventures; typical male and female names; and tables for randomly determining morphology/body type, deformities, and mutations.
This mini-sourcebook has been specifically designed for use with the Pathfinder Roleplaying Game but can be used with any OGL-based game pretty much as-is and easily adapted to any related or successor systems.