Humans are dead, and are be replaced by animal.

A long time ago, humanity fucked up the climate. This left the animals underground as the last remaining civilization. This is the story of how they climbed back to the top, and established a better world from the ashes of what once was.

Many scientists were trapped underneath as they were conducting experiments discerning the origin of life. Based in the south pole off the Bellingshausen sea, they had many reasources and transit lines on the surface to communicate.

They built a large underwater dome, and bore out several tunnels

The human population was unwilling to resolve their differences. They created a neural network machine to bring people together to make the right descisions to fix climate change. This AI contacted gained access to the whole internet, contacted world leaders, and managed to bring peace between them.

They made them think unbelievable things. Humans packed bombs full of snow and chemicals and agreed to dropp them all across their own cities. Human consumption, production, pollution, stopped everywhere at once. The massive networks and pipes and wires that nourished humanity were torn to shreds, and in a year, humans submitted to extinction.

There existed a clan of animals who were very harsh and mean. The underground wilderness was extremely cold, and the near-constant snow cycle meant that only the toughest survived.

Scruffy owls, snow leopards, emperor penguins, arctic wolves, orca beasts, and the like roam the freezing wilds. They reign over the tundra, mountains, and ocean. There are also a few unfamiliar beasts. Their lands are circled by a thick glass barrier. The sky is gridded if you look closely, and pulsates various deep shades of blue. Deep under the snow, heat comes from the ground, and various lava floes pop on the survace. There are many plants who feed off of the warmth from these floes. Their production of oxygen and consumption of carbon maintains the balance with the mammals above.

"These animals feed off of each other. An established food chain with arctic grasses and seaweeds at the bottom, consumed by small mammals and fish, eaten by larger mammals and birds, hunted by yet even larger predators"... is what you would expect. Yet this ecosystem is filled with intelligent and collaborative creatures of different species.

 Order of seas left to right: Bellingshausen, Weddel, Ross

        (Toxic waste has left the surface of Antarctica uninhabitable, however, a massive shield of algae protects the underwater from radiation. somehow)

All mammals and birds live off of plants, fungi and fish. It's possible to gain energy from eating other animals, but the developed brains in these creatures feel immense amounts of anguish from... specifically eating other sentient animals. Not killing. Animals who eat sentient beings are often out of their minds.

They are remarkably human. Many creatures have advanced vocal chords and communication skills, perhaps from the extreme conditions they live in.  Many are bipedal, and have digits good enough to use tools.

Many eat fermented sushi.

Villages are few and far between. There is running water in the villages.

There is a ruined place of worship where cannibals hang out. It's thin, and half underground, and yet it is the only place where cannibals don't attack each other and speak words. They are very nice to outsiders and can easily explain what they are, but cannot explain why they are.

Maybe they're on the surface, actually, not underground. Set in antarctica. And maybe it's always night! Yeah! Now, why is it like that...? Because of an evil entity? Or maybe, chemical pollution? Or the sun blew up? Hmm.

Lekker - a cold-blooded lizard who calls the arctic his home-away-from-home. he is searching for the lost relic of the ancient south pole city. when not talking with friends of colleagues, he's hyper-focused on his goal, sometimes to a fault. he doesn't care what people think about him, he only cares about what they can offer to him. He'll die if he gets too cold, so he carries a sturdy lantern with him everywhere. The polar monsters could eat him in a single bite.

Dorst - a possum who's kind of pathetic, despite their clean hygene. they know what the right thing to do is but often lets fear make their descisions. cares deeply about whether people like them or not. they look cute, but no one ever calls them that. finds common archeological interests with Lekk.

Macbeth - strong crane fellow. his job is to stand around and be tall, and barely talk to people. he offers advice when asked, like a great sage. he feels deep pity for Lekk and Dorst and joins their party, for he sees them as weak and needing protection.

Valgie - warm-blooded snowy tiger. joins the adventure seeking something thrilling, or to die doing something interesting. she feels small under the scale of the universe, and knows that all life is temporary.

Gohr - Walking killer whale! They know the Sea. They understand the patterns of fish and wave cycles well from hunting in the ocean for a long time. Views life spiritually, and has faced many hardships. Immune to depression.

Yetl - Cool spanish bird. Just there to look fancy and be spanish. enjoys hot springs. Also Operates the train. Communicates in gestures. Lets people ride if they don't have enough money. Hates his boss.

These animals appear vaguely of surface origin, but they were created by human scientists. Inadvertently.

Recently, there’s been talk about whether all the intelligent animals should destroy themselves so that the feral animals shall live. altru-sadists, they call themselves. They keep going on about how the intelligent animal life system is hurting the environment. Will their beliefs ever catch on? Will they ever stop bothering everyone?