Setting:CATastrophe
In a world covered in endless water...
Animal eared people reign supreme.
After the polar icecaps melted, the world was flooded, and everyone died in the resulting blunder
Save for rock monsters, animal eared people, and some tenacious sea sponges, insects, and birds.
This is the world of CATastrophe.
Premise
The world of CATastrophe is a post-humanity world where pristine waters have flooded human cities, and where carefree kemonomimi spend most of their time swimming and sunbathing, and explore the ruins of human society for loot and adventure.
Background
At some point in the future, rogue nanites are killing humans en masse. Humanity turns to exactly the wrong group of scientists (essentially a personification of /tg/) to fix the problem. The solution they come up with is essentially to create a new breed of human that would be immune to the nanites, and also have animal ears. When he was kicked out of a meeting for suggesting that these kemonomimi be giant futas with expanding breasts featuring fuckable nipples, some say that Dr. Williams swore revenge against the scientists and began sabotaging the other scientist's work, creating monstrous silicon based creatures, and melting the polar icecaps. Whatever the case, the kemonomimi were soon left living alone in the ruins of a flooded human society, with nothing better to do than live every day like a beach party or explore ruins of this lost civilization.
Chloronated Ocean Alternate
Chlorine meteors hit future earth at both poles, melting the ice caps, chlorinating the ocean into pool water and filling the air with chlorine gas. Most aquatic wildlife died, including oxygen producing algae. The oxygen content of the air decreased as it filled with chlorine gas. Between the unbreathable air and the collapsing ecosystem, the world became inhospitable for humans. Humanity decided to use its collective literal last breath to create a successor that could survive in the new world. As humanity died, it dedicated all its resources to a group of scientists that created the kemonomimi as human society collapsed. The kemonomimi grew in number as humans died off, leaving the kemonomimi alone in a world that had essentially become a giant swimming pool.
(This was the original concept for CATastrophe, and though it was discarded as the setting moved on to bigger and better things, some people still liked the idea of turning the world into a giant swimming pool)