The Walking Dead game is available as an app for iPhone 4 and newer devices. Devices older than the iPhone 4 for the original Walking Dead game and the iPhone 4s for Walking Dead: Season 2 The Game are able to support the app, according to itunes.com.
The iTunes apps for the Walking Dead games include in app purchases for additional episodes. Each episodes builds the story line progressively, and Walking Dead: Season 2 The Game builds off of game decisions taking by the user in Walking Dead the game, according to iTunes.com. Both games will work on other Apple platforms as well.