Tokyo Jungle
Picture a world where mankind has died out, the zoo animals have escaped, house pets have gone feral, and your only goal is to survive. You start out as either a Pomeranian, or a Sika Deer, and as you complete specific missions with each animal, you unlock new animals to play as, even a Pachycephalosaurus, and a Velociraptor.
The game has a lot of goofball moments to it, like actually watching your animal sniff another animals ass before mounting it, trying to catch a Rabbit as a Chick, and apparently, The Omega Man.