I added in cats. They are very naughty and will run and jump everywhere. The jumping detection logic took some time to code. Cats can both jump up and down a reasonable height. However they still may screw up and lose balance or get stuck. Just like real cats!
Cats can be picked up and stored in inventory. Great for bringing your cat companion wherever you go. Make sure they don't fall off a cliff though.
Also, cats are not edible. You can't butcher meat from them.