Giants in the Earth: Baby, It's Cold Outside: Alan Dean Foster's Tran-ky-ky

The durable Alan Dean Foster has written novelizations for dozens of movies and TV shows. He's ubiquitous, especially in the scifi and fantasy genres, and if you've read a novelization of a scifi or fantasy flick or show in the past forty years, you're probably familiar with his work. Beyond those novelizations, he has his own scifi setting, the Humanx Commonwealth, a sprawling interstellar governing body put together by humans and their unexpectedly close friends and allies, the insect-like Thranx. Foster has set numerous novels in the Commonwealth, featuring an interesting variety of planets and cultures. My favorites, and the ones with which I'm most familiar, comprise the Icerigger trilogy: Icerigger, Mission to Moulokin, and The Deluge Drivers, set on the ice planet Tran-ky-ky. It's a fun series of adventures, with salesman Ethan Fortune (for quick stats, use the human Noble for Ethan newly arrived to Tran-ky-ky, or the human Knight after he has spent months among the Tran) and galactic adventurer Skua September (use the stats for the human Champion from Volo's Guide to Monsters) finding themselves stranded among the natives of Tran-ky-ky.

These natives, the Tran, resemble gray-furred bipedal great cats with wings, called dan, much like those of a flying squirrel, stretching from their wrists to their waists, and natural skates, called chiv, adapted from their three-clawed feet.

From Barlowe's Guide to Extraterrestrials, by Wayne Barlowe.

Much broader than humans and a bit taller, Tran are lighter-boned and thus not as massive as humans, proportionately speaking. In fact, Tran unfamiliar with humans will find them surprisingly strong and fast. This works in reverse, as well; humans may well be startled by being able to hold their own in fights with the hulking Tran. This isn't to downplay the ferocity of Tran, who pride themselves on their warrior abilities. In their element, they are deadly opponents.

From Barlowe's Guide to Extraterrestrials, by Wayne Barlowe. Not exactly how I pictured them, but still pretty close.

That element is brutal cold. Tran-ky-ky is well below freezing at its equator, and its poles are are cold beyond anything on Earth, including Antarctica. For the Tran, though, this is home. The great ice oceans are traversed easily by the Tran, as they race like Olympic speed skaters without effort, their dan serving to help move them at breathtaking speeds. For longer journeys, they build sail-driven ice rafts. On land, though, they are at a disadvantage, tiring quickly if they are forced to walk or climb; Tran cities have their streets ice-coated for this reason.

The Tran are a warrior culture. Their civilization is about as advanced as Earth's in the Middle Ages of Europe. Feudal city-states trade and, occasionally, war with each other, while hordes of nomadic Tran sweep across the globe, raiding and exacting tribute from settled regions.

Tran-ky-ky

Tran-ky-ky has an unusual ecosystem, with plants that grow quickly with large ice-bound root systems, such as the sausage-like and edible pika-pina and the much larger tree-sized pika-pedan that thrive on the ice, and fauna that fill many niches found in more balmy climes, including the predatory flying gattorbyn (stats as per blood hawk, with immunity to cold) and the enormous and dangerous slug-like stavanzer (stats as per purple worm, with immunity to cold). The kossief, a worm-like predator that burrows beneath the ice and ambushes those who tread upon the thin frozen crust it creates above it, uses the stats for the young remorhaz. The fauna of Tran-ky-ky are often akin to giant versions of terrestrial invertebrates. The Tran, oddly, don't seem to resemble any of the other life on the planet.

Tran Traits
Ability Score Increase Dexterity increases by 2, Constitution increases by 1
Age Tran age and live about the same as humans.
Alignment Tran are much like humans in temperament, with no inclination towards one alignment.
Size Tran are tall and broad by human standards, standing at least two meters tall. Due to being hollow-boned, however, they are light for their size, ranging from 120-150 pounds. Their size is Medium.
Speed Walking on ground is taxing for Tran, so their speed is 25 on dirt or rocky terrain. Their skating speed is 50.
Born to the Cold Tran are immune to natural cold, and resistant to magical cold. Tran don't tolerate heat well, and when the temperature climbs to above freezing they must make a DC 5 saving throw per hour or suffer a level of exhaustion.
Languages Tran can speak, read, and write their native language, as well as another dialect of Tran living near them. In a D&D setting, they speak, read, and write Common and their own language.