It is common practice to think of games, in their narrative capacity, as a purely mimetic form. A game places you in a fictional scenario, in the shoes of a character or characters through which you experience a phantasmal world. You interact directly with a world represented through the art direction, mechanical design, etc. of the game. To some, it may be satisfactory to leave it at that. However, recent trends in indie titles hint at a more experimental orientation to narrative which not only presents something new, but also warrants a revisiting of how exactly a story is experienced in an interactive framework. Such a revisitation reveals the simple classification of game narrative as mimetic is problematic.
Strategy games offer an excellent example. Starcraft, for instance, positions the player as the commander of their chosen faction. But the interface implies that the player's experience exceeds this characterization. The player is not an individual general in the thick of battle, or commanding from a field office. Rather, Starcraft, in accordance with the standards of the strategy genre, positions the player as an omnipotent eye in the sky, less a commander than a manifestation of the structure of command itself. Of course, such strategy games don't deploy this device as an experiment. Rather, the interface necessitates this godlike position.
It is similar in choice-driven RPGs. In addition to the strategy elements of equipping and commanding your party, games like Dragon Age or Pillars of Eternity afford player participation in the development of the story. Through her choices, the player has a certain role in writing the story. Again, this is necessitated by the interface of the game, the mechanics which allow the player to engage with the story at its mimetic level.
In literature, diegesis refers to a manner of storytelling whereby the story is recounted, as opposed to mimesis, in which the story is represented directly. In film, the term has a different meaning, referring to whether an element of the film takes place at the level of the story or the level of the reader. Music, for instance, which can be heard by the character is diegetic, while the music of the soundtrack, which can only be heard by the audience, is extradiegetic. Games are in the unique position to bring these two meanings together. To illustrate this point, one can turn to recent walking simulators such as Sunset and The Moon Sliver.
Sunset, Tale of Tales' quiet political romance of revolutionary failure, represents the juncture of diegesis in games. It sits on the border of mimesis and diegesis. At the purely mimetic, representational level, you are cast in the role of Angela, a young American expat in a communist Latin American republic. Angela works as a maid for Gabriel Ortega, a local aristocrat who, between appearances at concerts and gallery openings, is financing a revolution against the country's despotic US-backed dictator.
The game takes place in a series of half-hour episodes, in which the player is given a list of chores and more or less free reign of Gabriel's lavish apartment. The story is delivered in two ways: first through Angela's poetic commentary on Ortega, spurred by her existence in his living space, and then through entries in Angela's diary, which she can be inspired to write by sitting in Daniel's easy chair. This is diegesis in it's pure literary form. Angela recounts the game's story to the player in a space that is contextualized by but separate from actual gameplay. Thus, the narrative is diegetic, but you, the player, are still largely mimetic, her actions being represented through engagement in her chores. Even Angela's reflection in the glass surfaces around reinforce that you are Angela, and in fact the diary reveals that Angela herself is conscious of the apartment as a space that is separate from the action of the story.
The Moon Sliver goes a step further. You are left on an island with only the instruction to explore and, when night falls, enter the mountain. As you navigate the lonely beach, you uncover the story through letters and journal entries, as well as passages of prose that appear on screen as you move through significant areas. The cryptic narrative vaguely implies that you might be one of the characters about whom you are reading, but because your actions are not specifically contextualized within the narrative, you are kept at a distance. You are an observer, an audience to a story, merely following in the footsteps of a character whose ending has already been written.
In this sense, the player character is itself extradiegetic, to some extent, but not entirely. Unlike Starcraft, in which the extradiegetic orientation of the player is purely mechanical, The Moon Sliver intentionally blurs the line between diegesis and mimesis, allowing the player to exist in a sort of narrative limbo, somewhere between the lines of text and the physical game world.
This narrative mechanism is peculiar to the interactive immersion of games, and opens the door to new possibilities for storytelling and avant garde experimentation in the medium. Even more fundamental than the pretentious potential for deconstructionism and semiotics within games as literature, the quasi-diegetic space games naturally occupy, as entities of both story and interface, allows for new questions of narrative altogether.
The task of answering these narrative questions falls, as usual, to the writers.