There’s a number of pet games that have been a huge success on the iOS platform – those games in which the users create, customize and use their pets which are stored on a central server.
Here’s an example game called iPokemon by Kaijie Yu that was originally created as a school project that unfortunately never reached the app store because of issues with using the name Pokemon.
In iPokemon the user creates, improves, and battles different Pokemon characters that are stored on a server. In addition location services are used so you can see the Pokemons within a specific area.
This is a very in-depth app that uses a number of custom controls, and open source projects including Cocos2D and AFNetworking.
Here’s a video demonstrating the iPokemon game:
You can find the iPokemon homepage on the Kjuly site here.
You can find the iPokemon app code on Github here.
You can find the server code for storing the Pokemons on Github here.
A great example of a persistent “pet” type game.