Finally, the Sims Unleashed on Sims 2
Pets is really fun because you can make your own species like a doberman-poodle mix just by mixing up the fur designs and colours. I also like that the pets can interact with toddlers, like the toddlers can hug them and the dog can lick the toddler which is pretty cute.
Whats annoying about the game is that the pets can make a total mess of the house so you have to train which can take ages and it drove me crazy.
I still love though ;)