>a technologically advanced civilization (the Aliens) make contact with Earth; a small, mountainous island is their original landing site on this new planet
>they decide to breed the creatures discovered on Earth to take on the Aliens' characteristics and, when they're ready, teach them to communicate
>they chose mammals, as they already resembled them the most, creating the Animals
>the Animals evolve, with the Aliens' guidance, to walk on two legs, use tools and speak in the Aliens' language, as well as gradually move towards being the same body size between different species
>this causes benign quirks in the Animals' evolution, such as one species derived from feline eventually forming pink fur, or another from bats losing the bones in their wings
>the Aliens help the Animals build civilization, creating houses meant to accommodate the needs of both races (for want of a better word)
>divisions formed between the Animals and Aliens when they realized many of their needs are incompatible, such as the Aliens' lack of a need for sleep and a general feeling among the Animals of some kind of a secret being kept from them
>it is soon discovered that the Aliens were performing experiments on some Animals, making them unrecognizable to the other Animals
>this leads to a brutal, planet-wide conflict that lasted an untold length of time
>though they knew they had the upper hand, the Aliens retreat to the first landing site (still untouched by the Animals at this point), filled with sorrow of what they had done to their long-time friends
>the Aliens decided to no longer interfere in the Animals' affairs
>the conflict decimated the Animals' population and left little to no sign of their society to be found
