Fort: Cats & Dogs Expansion adds two modules to the Fort base game: dogs and cats. You can use one or both, as desired.

Dogs are loyal. If you play one, it will (usually) go stay in your doghouse, but they're fussy, so you can play a dog only if you meet its needs. Neglect a dog, and it'll wander off. At game end, whoever has the most dogs in their doghouse scores seven points!

Cats are fickle. Their actions happen at specific times, and they move around a lot. Cats will be attracted to a different player if their yard has cards of specific suits, even if the cat's current owner has them, too. The more cats you have at the end of the game, though, the more points you score.