There's humans from earth cybernetically modified to a horrific extent, and the game takes place in the distant future.
- Confirmed, to an extent.
Flavor text says some creatures are Trebhum creations, implying they were advanced enough long ago to have genetic engineering. This could explain their ability to mutate instantly, they engineered themselves to become adaptable to a dying world.
It's the only animal not to flee from the Cylinder as it can fly above it, it targets Trebhum in particular, its design is alien-looking even compared to the rest of the animals and it has Gravity Master powers that can in no way be a mere natural evolution. Perhaps it is another of the Cylinder's monstrous creations.
According to the description of the Iridescent skin mutation, it makes Trebhum "shiny and sparky and very attractive, as all Trebhum should be". In-game, the Iridescent skin is cosmetic and doesn't serve a really particular role, though that might be because the Trebhum you're controlling aren't supposed to get the mutation yet because they're too young to know the real purpose of the mutation, let alone take advantage of. According to what remains of the Trebhum culture, Trebhum associate sparkles with beauty and attractivity, which is what happens when you get the Iridescent skin. With all that said, it wouldn't be too much of a stretch to speculate that during mating season, Trebhum would mutate iridescent skin in order to attract mates.
Probably, because the Trebhum planet has very high gravity and all the animals and plants are much smaller, and a side effect of high gravity is the denser atmosphere that allows creatures like Zooshgargs and Onkifurts to fly.
And the ringed planet in the sky actually IS Saturn, explaining why human-like creatures are in such proximity.
