A Changed World

"Ever since I could remember, I've loved big cats. I've always wanted to know what it was like to be one, to have that power and freedom, but I never expected my wish to come true...sort of."

Finn was half way through his third year of high school when they took him. when he woke up, he was in a glass box, about 25cm in length and with four paws and a tail.
After about 2 years of captivity under constant suppression, with no hope of freedom in sight, the Earth starts to change and grow. Land splits and creates towering mountain ranges and impossibly large ravines, seas become deeper and wider and give way to small and large islands. When the Earth has settled down, there are no humans felt alive. All that's left are the animals.
How will Finn and the others survive in this new and exciting world when Earth becomes connected to another planet and they meet the other inhabitants