Aggregates are composite creatures that result from the changes that develop from a host and a symbiont living as one. Rather than one individual host creature being infected by a single parasite, the aggregation process describes how two species merge over generations. Many aggregates do not survive the initial infection or bonding process, and it is only through large numbers of the host species and symbiont species combining that a new species eventually develops.

This publication is dedicated to providing useful information, game content, and ideas to players of modern, science fiction, and post-apocalyptic table-top and role-playing games in general and to fans of Goblinoid Games’ Mutant Future retroclone of classic Gamma World in particular. The rules contained herein are compatible with it and any others that use the “Basic” OGL/d20 RPG system.