I've always been a big fan of "Cat: A Little Game About Little Heroes" by John wick, and The Secret Of Cats scratches a very similar itch with style and panache within the Fate Core system.
It features a ritual magic system that will be eerily familiar to anyone with cats in their lives, and is chock full of adventure.
Basically if you or your players look at this comic - http://www.asofterworld.com/index.php?id=6 - and think "Hell. Yes." then this is a good game for you.