From the original document:
You play while you stroll of a summer's evening. The in-game events happen in the real-world setting. Like you can say "see that place in the fence back there where the lilac bushes are? There are 2 cats back there, whispering, and they give you a dirty look." You can say "I jump up onto the roof, see right there, and then onto the dormer, and can I make it onto the roof next door?" Like that.
The PCs are nighttime animals, specifically raccoons, rabbits, skunks and opossums. All of 'em can run and jump and hide and see in the dark and smell smells and stuff. Raccoons also have opposable thumbs, skunks have stink power, opossums can dangle by their tails, and rabbits can run fast and jump real high.
They save the world! Something bad's going on, like there's a sorcerous hurricane devastating the neighborhood, or somebody's making all the dogs mean instead of just friendly, curious and kinda dumb, or the cats are doing their thing about who's king of the cats and it's turning ugly and spilling over into inter-species violence. Conveniently enough, whoever's behind it is headquartered at the destination of your stroll. (Many is the world-threatening plot hatched in and around our local popcycle store or our favorite video rental place!) Only the nighttime animal PCs realize just how serious it is, and if they don't solve it, it'll be bad for everybody.