[AndreaDraco83]

I can't really compare games - I'm referring to the adventure genre, primary - to movies or books: they're different media and they've a very different range of scope.

I limit myself to three consideration:

1) In the modern theory of art, literature specifically, the recreational (sorry: I don't find a better word for the Italian "ludico") aspect of the art's fruition is something not only accepted but also celebrated. In this regard, a game doesn't differ much from a book or movie.
2) The adventure genre reminds me, on a way, of the ancient storytelling of campfire tales (a story created by an author in which any of the listeners can contribute), thus of roleplaying in its basic/non-regulated form; on the other way, the adventure genre realizes the promise of interactive fiction, 'cause it menages to create a story which can't be closed without the help of the gamer: but isn't this help similar to the effort of a reader, or a viewer? In some ways, the answer is yes: the reader/viewer/gamer can turn off the PC/close the book/exit the cinema thus leaving incomplete the story. The gamer differs from the other two 'cause, if he choose to subscribe the deal and continue through the game, he will be a lot more challenged than a reader (with the given exceptions)
3) The adventure genre makes the player think literally, imaginatively, laterally, and so on... The story is already written but it gives the impression that is not (and, in some case, it isn't), 'cause its course is left to be decided by him. If a game contemplates only one possible way to finish the story, it will still be interactive fiction 'cause the way I played the game surely differs from all other's ways; if a game contemplates multiple endings, parts of the story that can be missed, details not necessary, it is an example of interactive fiction as well, of course.

So the point is: every way to tell a story - book, movie or game; even the campfire tale - can be (must be, in my opinion) interactive, 'cause it demands that the reader/viewer/gamer not only cooperates to the storytelling, not only agrees to continue through the story, but also signifies the story with his very own point of view. So, literature, cinema, adventures are only different ways to tell a story, diverse media with the same aim.