The tuat are a reptilian race of humanoids, standing about six feet tall, covered in scales, who typically build their villages near or on water. They prefer warmer temperatures and don't do well in cold. They have a tribal culture built around clutches, which are extended family groups.
Right off the bat, we've got a couple things we can work into a race-class. One, they're comfortable near water, so maybe they should have an amphibious ability of some kind: water breathing, a bonus to Strength checks to swim, something like that. Two, they can take a penalty of some kind if they're in a cold environment or if they take cold damage.
Tuat tend to not use very much metal, as they prefer to use materials they find in the natural environment. Where humans or demi-humans would use metal, tuat typically use carved or carefully-broken stone. Tuat spend much of their time away from what most would consider civilization. Their structures and gear look primitive, but are sturdy and built to last.
There's some more we can use. Since tuat don't use a lot of metal, it's really easy to set their weapon and armor proficiencies; leather armor and shields for armor, and spears, bows, daggers, or similar weapons that could easily be made of raw wood, leather, and stone.
In Dark Dungeons and similar OSR systems, it seems like elves are shown more as an ethereal, magical race than the in-touch with nature, wild elves that are more common in systems like D&D 3.5 and 4E. For my setting, I see the tuat as kind of taking over that niche. I'll get into how that comparison to elves will affect the rest of the tuat stats in the next installment, along with some examples to show the kind of iconic characters I've been thinking of when working on this race.