Catz 3 is a virtual pet program wherein the player raises a kitten to adulthood. The player can have as many petz as they want and can play with up to 3 at a time. There are 10 different breeds of catz to choose from and more that can be downloaded from online sources. Male and female catz can breed and have unique kittens, mixing their breeds. Many people online run their own breeders where you can download and trade unique kittens from other owners.

There are multiple play areas to choose from including a beach, backyard, kitchen, and living room. There are also lots of toyz for your catz to play with and clothing if you like to dress up your animals. Some catz can be trained to do tricks, and their behavior is based on how well they're treated, and how much attention they get. If they are abused, they will run away from home.

This program integrates smoothly with it's counterpart Dogz 3 allowing you to play with your dogz and catz at the same time. No weird inter-breeding though! Other features include family history trees, a simple webpage creator for showing off one's petz, and the option to make an "adoption kit," so that friends can try the program too.