People of K'n-yan

The People of K'n-yan—or K'n-yanians—are humans who live in a blue-lit, subterranean world beneath Oklahoma. It is said that they cut ties to the outside world around the time that Atlantis sank—approx. 10,000 BC.—and their society has since stagnated, loosing most of its art, science, and magic, though still considered "advanced" by our standards.

In the RPG...

In the old Malleus Monstrorum, K'n-yanians used to have the same stats as humans, save for higher INT and POW. In the 7e edition, every stat is now different except for SIZ, and they are all higher.

    K'n-yanians have some psychic abilities such as telepathy and dematerialization. Telepathy is just used for communication, though dematerialization has many other uses—even harmful ones. If an unwilling target is chosen, they can only resist with an opposed POW roll, so if this is an Investigator, they'd only have a 24% chance (on average) to resist. They'd also lose 1D6 Sanity points.

    K'n-yanians also have disintegrator rays, which does hit-point and APP damage. This weapon used to have a mere 10% chance to hit, though this has now been increased to 35%. My favourite part about this weapon is that a fumble results in the device exploding, causing a massive 8D10 damage! It says this is just to the wielder, but I feel it would be more exciting to give it at least some area of effect.

    One other ability—which I almost missed seeing and is new to the 7e Malleus Monstrorum—is a psychic attack which takes 1D10 magic points. It requires an opposed POW roll, so would have the same 24% chance of winning as above, so would be a pretty effective attack. Especially seeing as an average Investigator only has 10 magic-points to begin with.

In a video game...

While K'n-yanians themselves are fairly unremarkable, their "world" could be an interesting locale in a video game. Not only is it subterranean and blue-lit, but the peoples partake in games of strength, skill, and stamina, as well as various mind-altering substances. They worship numerous different deities, and they are also great Dreamers and can remain in dream-like trances for years at a time. On the darker side, they've also devised many forms of torture and scientific experimentation, including re-animation. As well as all this, they ride Gyaa-yothn. K'n-yan is also connected to N'kai, which contains Formless Spawn.

In a film...

Personally, I think an underground, oddly-dressed race of humans would come across as goofy in a film, even if the more horror-themed side of their culture was put front-and-centre.