Writing in games isn't about plot. Hell, good writing itself is not entirely about plot.
For games, it's about the experience of the narrative, and the experience and feel of the story, be they the events, the gathering of information or other such alike things. Comparing it to a book is rough, because the experience of reading is not a vastly explored part of prose. A writer cannot so easily account for when and where you turn the page. The closest thing is the effect of voice and world building upon the reader.
For a small example, there isn't much a plot to a game like Limbo, but it feels like it's about something and it conveys that through the experience of playing the game. You could assemble a plot yourself through the experience of the game and tell your idea of the story, though that story is never fully present to be shown. In a way, game narrative is about the experience that leads to the story, rather than something like writing and staging the story. In a novel, perhaps you try to describe a never ending limbo. In a film, you show a weird place of limbo. In Limbo, the limbo is the cyclical nature of the game, where the end of the level never really occurs, where information is only that which you can discern from tepid, scattered and sometimes confusing clues.
