Swapship Troopers was - first and foremost - a solid science fiction adventure tale, openly inspired by Paul Verhoeven's film version of Robert A. Heinlein's literary classic. Also to my delight, the gender-swap element is not only a well-done bit of transgender erotica, but it is actually integral to the story.
Walker Long weaves multiple genres through his tale, including science fiction, military thriller, transgender erotica, and even genuine romance. Taking its cue from the source material, Swapship Troopers introduces us to a group of Space Marines whose job it is to protect against a monstrous insectile alien invasion. The opening battle is frantic, bloody, and exhilarating, effectively establishing the concept, the characters, and the stakes. With humanity triumphant once again, the Space Marines are granted some much-needed relaxation, courtesy of a mysterious pink serum. Half the crew is injected, turning them into wholly feminine versions of themselves, with the other half of the crew picking bedmates according to their rank.
The transformation process is nicely detailed, with a solid sci-fi explanation for how it works (and how the blue serum reverses it), and the selection process is suitably amusing. These newly formed women are still Space Marines, and still know how to follow orders, so succumbing to their sexual urges is not as awkward as you generally find in such stories.
What makes the story stand out is the core relationship between a Private and his Lieutenant, an opportunistic gender-swapped encounter that reveals something more about both of them. As a heterosexual romance blossoms, Walker Long does a wonderful job of exploring how that impacts two men, two Space Marines, both in the chain of command and on the field of battle. The character development here is fantastic, and Private Quantrill's embracing of his feminine side is just a strong. There is no instant acceptance here, but neither is there prolonged angst. Everything develops naturally, heading towards a dangerous confrontation that will redefine their personal and professional relationship.
Swapship Troopers is a smart, erotic homage to the science fiction genre, and a gender-swap story that manages to be both exciting and erotic where it needs to be, moving seamlessly between action in the field and action in the bedroom. A fun read that is sure to entertain.