Far into the future on the Earth we know and love (at least insofar as it sustains us), there have been vast technological advances. The Earth no longer suffers from a surplus of greenhouse gasses, the human-created warming of the Earth and melting of the icecaps have been halted (and even reversed in some places), and the distribution of food and wealth have become far more efficient and equitable for the past (almost) century. If this sounds like some sort of quasi-utopia, well, you'd be at least mostly right. (Somewhat.) However, there has also been a boon in the sciences of AI development, and perhaps the most amazing thing that has been done is the creation of machines that can interface directly with a human's mind and take commands directly from their neural output. While this has allowed some truly amazing things with 3D and alternate reality gaming... it has also paved the way for some other inventions as well. And this, is where our story picks up...
One dabbling scientist who was a leader in his field of science dealing with the aforementioned neural interfaces happened to have a friend who was a leader in his field of terraforming technology. This is the same tech that was used to colonize Mars and make portions of the Moon hospitable to human settlements. A third scientist, who it would be a stretch to call a friend, happened to be developing some tech that could allow some limited reality warping. And when I say limited, I mean that he had purposefully implemented a ton of safeguards to assure that his experiments didn't get out of hand. He was able to manipulate matter on the quantum level and shift and mold it to within the stated parameters. Think of the matter creating technology of a holodeck on Star Trek but with the Fullmetal Alchemist-esque proviso that matter cannot be made, simply altered and that in order to make something, something of equal value must be exchanged.
One of this last scientist's assistants was not exactly the most careful or scrupulous dude you'd ever met, but she did have the knowledge that the previous two scientists and their work was stored in a database that was secured by the same data storage center that stored all of the scientist's work that she herself worked for. So, with all that combined knowledge in one place, she was able to crack through the security of said database, and pilfer the combined resources of all three incredible scientific minds. Now, with food, money, space, and climate being non-issues, she set her sights much much higher. She wanted to craft a machine that could interface with a mind and then create in reality those exact desires! After years of hiding out and dodging the inquiries of any who might try to suss out what she was up to, she was finally able to create what she liked to refer to as the Dream Engine. A bit hokey, maybe, but she felt like it summed up everything about it that she wanted it to be. Oh... did I happen to mention that this chick put her machine on an orbital station rotating in opposition to the moon? No? Well, that's likely an important detail.
On one fateful day of testing and re-configuring the surrounding environment to her wishes, she went a little bit mad with excitement and decided to turn off all but one safeguard: the one that stopped the machine from killing any Homo Sapien. However, with all of those safeguards off... and her mind alight with ideas and images of everything that this most perfect of machines could do, it is a surprise to no one that things didn't go exactly as planned.
• "What if... the Earth were opposite?"
With but one thought, and an entirely too vague one at that, the machine went to work changing all the water to land, all the land to water. It killed every living species on the planet that wasn't a human, and resurrected a scad of those that had been extinct for milenia... But, of course, it couldn't just make something from nothing. So, the earth was moved and shaped and sunk and raised in order to give us the map shown below. It's not perfect, as no machines made by man are, and of course the water isn't all as backward as one expects... but it is what the Dream Engine made it.
Now, one asks, what is the population of the world like? What happened to all these people that the machine couldn't kill? And what influence will their languages of origin have when tossed into this strange new world? Well... the machine also had something to say about population density. Since numbers can't be made opposite, it did however decide that the population density must be vastly smaller by attempting to make sure that centers of population on the old world were devoid of human life on the new one. Oh, and everyone that didn't fit in the new schema? Well, they are in hibernation on the once colonized terraformed side of the moon. All humans, including the female assistant who has yet to be named, had their minds wiped so that what had been full... was now empty. That includes, of course, all the people that got plopped down in the various settlements across the world. A feature that makes all Carnassians on equal (and strange) linguistic and mnemonic footings.
The world that I refer to as Carnassus is one in which some vestiges of the bygone Earth are still present. Ruins of decimated cities might still be found as they were ground up and spit out across the globe to make the new landscape. Entire continents complete with their cities might still exist on the ocean floor somewhere for all I know. But, the one feature is that every language that is born on Carnassus is by its nature a language isolate as the focus on this place is maybe a couple hundred years after it was all crafted. Now, yes, there will be dinosaurs somewhere on the planet... but due to the climate of Carnassus, I have no idea where that will be yet, but I really need them to exist somewhere.
• Maps, etc.
This map shows all of the continents, as well as the equator and tropics. The map isn't 100% of my invention... in fact none of the cool bits of satellite-looking imagery are. I happened to find a really sweet rendering of a reversed Earth map someone online had made and then heavily heavily altered it.
Please, feel free to help me out in refining this idea in anyway you please. I need the most help with climate stuff... but also ecology and what some fun extinct plants and animals might be to spatter across the globe. As far as languages go, all of the languages that I have been crafting can get smashed onto the planet in one place or another, just so long as the clusters of folks who speak them are not in contact with one another and are grouped around in pretty disparate locales. Ask and or suggest me anything!
• https://www.frathwiki.com/Carnassus — A link to the FrathWiki page about the conplanet. At the moment, it has basically no info that isn't already here, but there is some info on the side-bar... which is mostly the same as Earth's.