Had the game been so vulgar as to mimic any movies, there’d have been a Hollywood version years ago. But the secret of it success is that, while full of historical parallels, it tells its story as if games were the only medium on Earth. There are no cut scenes, no paragraphs of exposition to read, and the closest you’ll get to pop-culture references are Orwell and H.G. Wells. In their place, Valve’s artists, technicians, storytellers, and sound engineers create a unique milieu: a distinctly Soviet metropolis being literally consumed by alien architecture.
It tells its story as if games were the only medium on Earth. That is a really great observation, even if it’s not true, and I’m not sure it is. (Among other things, the story, characters and dialogue are pretty straightforwardly modeled on the tropes of action flicks.) But the gist of the point — that what makes a game interesting is its desire to be gamelike, to take its reference points from other games, to regard gameness as central — is nicely put.