The "semi-sequel" to THE DESERT is being tentatively titled ACHERON. (Loyal readers will get the reference.) I'm currently writing both the novel and the screenplay, and am more than halfway complete with both.
Although it deals with similar themes, it only contains one character crossover from THE DESERT, and that happens at the end. I say "semi-sequel" in that the events of ACHERON are linked to something that happened in THE DESERT, but you will not have had to read it beforehand.
I have not begun to shop around either the book or screenplay, but interested parties can contact me at email@example.com.