From publisher blurb:
Humans have a tendency to make mistakes, sometimes ones that have far-reaching and unforeseen effects. In our history we have wiped out entire species, transported exotic animals to places they really do not belong, accidently spread disease across the globe, and created technologies that we can barely control. In the future, this trend will continue, for it is human to err, especially when doing so with the best of intentions. What humans do, one can expect other sapient species have also done in the vastness of explored space.
This publication contains three iconically creepy and dangerous alien lifeforms that can be inserted into any OGL games. On the one hand they are commentaries, as good sci-fi often is, on the dangers of technology either run amok or casually handled. On the other hand they are nasty critters that will happily eat your face off and are thus perfect fodder for games of suspense and terror.
First is the Balthusian Bilge Rat, a hazardous xenomorphic leftover from a pre-human star-faring civilization, that assumes three successively more dangerous forms throughout its lifespan.
Second is the Donner Virus, a dangerous viral infection that drives its victims to suicidal Violence, and for which we have included both a sample victim and a template that can be used to create custom monsters.
Third is the predatory Hunter, an artificial lifeform created by an ancient race and placed throughout their long dead worlds-spanning civilization to guard important sites and to track intruders until it has killed them all.