The Sime~Gen Universe, created by Jacqueline Lichtenberg, involves a future where humanity is divided into two subspecies or "larities". Gens look like ordinary humans and produce excess quantities of a life energy called selyn. Simes, who have tentacled arms, must take selyn from Gens in order to survive. If the Gen is frightened and resisting when selyn is taken, the Gen dies. The series chronicles the history of the two subspecies' search for coexistence.[1][2][3][4][5]
Simes and Gens have traditionally lived in separate territories. Simes raise Gens like food animals in pens. Children might become either Sime or Gen at puberty, and free Gens kill their children in self-defense if they start to change—if the child becomes Sime, it might take selyn from parents or loved ones, killing them.
Simes who can take selyn from frightened Gens without killing them are "channels". They can pass the selyn gathered to other Simes. The discovery of the channels leads to Unity. Sime and Gen territories declare an uneasy truce, and channels strive to assist both sides.
Lichtenberg began the series in the late 1960s as part of a creative writing class, putting it aside briefly to work on the Kraith Star Trek fan fiction series.
There is also an extensive collection of fan-fiction available online, particularly through the official fan site at http://www.simegen.com
The next volume, To Kiss or To Kill, which contains 2 novels and a short story, was expected to be published by Meisha Merlin Publishing Inc. in June 2006. The title novel is authored by Jean Lorrah, and the volume also contains a short story, Best of Fools, by Jean Lorrah, and the novel Personal Recognizance by Jacqueline Lichtenberg. Another volume, "The Farris Channel", is completed but unpublished.