They're alive but not living, ghosts haunting an empty purgatory, delaying the inevitable. But in the unflinching vision of a zombie apocalypse outlined by writer Robert Kirkman and artists Tony Moore and Charlie Adlard in their comic-book series - now adapted for TV as well as into this episodic adventure game by Telltale Games - it also applies to the survivors themselves. On the surface, it refers to the shambling undead that have overrun the American South (and for all we know, the rest of the world besides) the survivors call them 'walkers'. There's a deliberate and sad irony to the title of The Walking Dead.