Some good virtual pet adoption games include Neopets, Webkinz and Furry Paws. Other games that involve virtual pet care include PetVille and PsyPets. All of these games are browser-based and appropriate for children or adults.
Neopets is a game with fictional pet species, such as the dog-like Gelert, the hamster-like Meerca and the fish-like Koi. Webkinz features realistic pets but requires that the player purchase a real-life stuffed animal as the counterpart to their online pet.
Furry Paws is a dog adoption game that features breeding and showing strategy. PetVille is a Facebook game geared toward small children who love decorating their pet's home, while PsyPets is geared toward an older audience with Maslow's hierarchy of needs forming the basis for pets' behavior in-game.