Sandbox Games and the Non-Linear Story

There's a fascinating post on my son's blog at passion4games which is all to do with those games that have nonlinear stories - as he says, writing for such games is difficult, because they have 'numerous branching storylines' - the player enters the world of the game, but doesn't follow the story through in a linear fashion - instead the player explores a whole new world. As he says, this is an experience that other media can't provide - not even the book - although the potential for such interactive books may be there in the future, with the advent of e-readers.
On the other hand, would such books have any appeal to most readers? Or is such a structure very much something which is better realised through this new and fascinating medium of the complex and intensely creative world of video games - a world which is, moreover, developing all the time.
And isn't this something that - sooner or later - we as writers are going to have to address, a new medium that we ignore at our peril. It seems to me that most people of a certain age still assume that video games are the province of geeks who sit alone in their rooms writing code. But the new games are nothing less than artforms in their own right. And if we want to see video games developing in even more creative ways in the future, then as writers, we surely have to get involved.