This first book in the Callisto series mimics Edgar Rice Burrough's A PRINCESS OF MARS to a certain extent. John Dark, a soldier in Vietnam, comes across some ancient runes and is whisked away to Callisto, a moon of Jupiter. There, he's almost killed by a vicious predator that's sort of a cross between a Saber-toothed tiger and a reptile. In the nick of time he's rescued by an insect-like race, though they keep him as a slave for months. He manages to befriend one of them, Koja, who eventually sets him free. There are several sentient species on this moon and they all speak the same language, including the insectoids. And even though they are far more distant from the sun, the land is tropical and gets its illumination from the amber mist that encircles the globe.
Jandar encounters Princess Darloona. Her kingdom had been conquered months before, so she's somewhat displaced. And although he's smitten with her he does the absolute worst thing in her eyes-- he brags about his fighting prowess, which is a "no no" on this world. He becomes a fugitive, so must disguise himself, as there are no blue-eyed, blonde-haired people on this planet. He befriends a swordmaster, who teaches him the artform. This comes in handy, as this is the weapon most everyone uses. However, the novel remains open-ended, as the last thing he sees is described as something unbearable, which probably has to relate to the love of of his life.
Fans of Edgar Rice Burroughs will love this, as Lin Carter (along with Philip Jose Farmer) is one of the authors who manages to capture that same "feel". Recommended.