By taking the concept of choice and mapping it onto spatial relativity, The Stanley Parable has created an extended metaphor that comments on the whole concept of choice in video games.
When we think of choices in games, the image we usually imagine is a clearly marked out situation with two or more responses represented by buttons or by on-screen options in the UI. The player then makes a choice by pressing the corresponding button or clicking on the preferred option. These choices then dictate how the plot of the game's story will unfold. Think of the Mass Effect series in this regard or how it is wonderfully parodied in the walk and talk opening of Saints Row IV. These are generally moments different from the game's standard style of play and need to be represented by their own system, one that is essentially separate from the rest of the game. It is as if the the characters have been brought into a sort of fugue state outside the normal game space, and in most cases, outside of the passage of time.
The Stanley Parable belongs to that collection of games based on genre minimalism that I've been calling the first person walker. While the game does have one click interactions that can open doors (in some cases) or push buttons (to little or no effect), most of the game is spent walking around corridors. Unlike other examples of the genre it doesn't seek to minimalize a genre, only a certain aspect of it, by turning what was once an outside consideration into a physical aspect of the play space. What were once represented by a button appearing on the user interface now is literally represented as branching paths.
Video games, of course, are very good at representing space. They understand movement within defined spaces and the relative space between objects because these are things that are easy to model. By taking the concept of choice and mapping it onto spatial relativity, The Stanley Parable has created an extended metaphor that comments on the whole concept of choice in video games.
Take the first presented choice in the game. The image of two doors on the other side of a room: one on the left and one on the right. We are given two options, but by themselves, this is an utterly meaningless choice. There is nothing to distinguish one door from the other and therefore the choice lacks context, which means the player cannot make an informed decision. Likewise, though, two buttons appearing on screen to signify two different courses of action by themselves are meaningless. This is where the Narrator steps in. Up until this point, he has been explaining Stanley's backstory (the character that you are playing as) and the present circumstances that Stanley finds himself in. Then the player enters the room with two doors, and the Narrator says, "Stanley took the door on the left."
Suddenly, the player has context for his choice. With regards to the fictional universe of The Stanley Parable, we know that the meeting room is through the door on the left, but we have no idea what is through the door on the right. The context that we are given, however, is not about the spatial relationship of various rooms but about whether or not you will obey the Narrator.
For all that the The Stanley Parable has to say on video game agency and the tug-of-war between designer and player, the game does not address the specific ludic apparatus which it is using. The two doors are the button prompts of previous games that offer such choices, and the Narrator provides the narrative context of those button prompts. Through other lenses, the Narrator becomes other aspects of the player/designer/game relationship, but for this, he is the context that the game's story provides the player so that they can make informed decisions.
If we look at the results of the player's decisions, we find that feedback on them is rather immediate and is also drastically different depending on which option is taken. The player finds themselves in different areas, looking at different rooms and faced with new choices that they would not have faced otherwise. Following the metaphor of how choices function in games, this already makes The Stanley Parable far more dynamic than most other games that provide choice. Mass Effect presents the player with choices, but in the end, that player will end up in the same areas, fighting the same enemies, and having a very similar experience to players who make different choices. There are cosmetic differences in these outcomes and elements of narrative change slightly, but nothing that will change the fundamental structure of the plot.
Now, The Stanley Parable is shorter and less complex than Mass Effect. It has more elbow room to work with on a basic structural level. There are less elements that need to be considered for each choice that the player is given. It's true, but it is also an incomplete explanation. Much of The Stanley Parable finds the player treading through the same areas, areas that are just seen in a different context because of the commentary of the Narrator. One series of choices will have the Narrator realize you are a real person and send the player back the way that they came. Another will force the player to follow a yellow line through the same sections of the office complex the game takes place in.
The Stanley Parable is a game about choice. The Narrator reminds the player of this fact over and over, just in case one should happen to forget. Whether he is defied to the end, followed to the letter, or somewhere in between, the Narrator makes it clear that each path represents something about the concept of choices in video games. What it does not do is explain the mechanics of how it comes about from the player's perspective, or rather, how it comes about on the basis of the player choosing one of the predetermined options created by the game. As a second narrator is so kind to point out in one ending: "Every path you can walk has been created for you long in advance."
So far, I have been describing choice in video games the same way many video games have chosen to present it themselves, providing clearly marked moments that are identifiable as a choice with enough overt contextualization for the player to make an informed decision. The Stanley Parable contains other types of plot-based decisions, though. The first clearly presented choice in the game is the room with two doors in which the Narrator tells you to take the door on the left. However, it is not really the first choice in the game. The first choice in the game is to not leave Stanley's office at all or to move forward with the proceedings. After the opening cutscene, the Narrator says, "He got up from his desk and stepped out of his office." The player is still in Stanley's office at this point. The Narrator has already begun dictating the story ahead of time. But the player doesn't yet know that they can defy the Narrator. They may not even notice there is something to defy.
Choosing to not leave the office by closing the door instead leads to an ending. After some narration, the game will restart, and you end up right back where you were with the same choice before you. For all intents and purposes, this is a hidden choice because the materials needed to effect the story are present but are not obvious.
Another type of choice of this sort appears in a warehouse that includes a crate lift. The player can choose to have Stanley step off it at any time and either drop to a catwalk below or to fall to his death. The catwalk, while not directly mentioned by the Narrator, presents itself as an option for the player to take. Presumably players will find that they can fall to their death through the normal course of experimentation and play. It makes perfect sense for this to be an option and is a perfectly acceptable ending for the game, but, again, it is not presented overtly as a choice.
If you want to talk about endings that are not obvious, the heaven ending requires multiple playthroughs, clicking on random computers that the player doesn't know that they can interact with or that anything will result from doing so in the very long term. But in the end, doing so is an acceptable choice with a real consequence and reward.
Another choice requires more out-of-the-box thinking. When presented with a ringing telephone, the player can unplug it instead. This, again, is never addressed as an option. In this narrative path, the Narrator has given up dictating through his voice as narrator what Stanley is going to do next and is instead talking directly to him, telling to pick up the phone. The phone cord is never mentioned and yet is still an option that the player can find for themselves.
There are choices that "break" the game by putting the character in a position where the player has no choice but to restart. Walking out of the open window into a completely white space or following when Stanley is crushed to when the player finds themselves looking at complete blackness. These are, intentionally or not, a part of the possibility space of the video game. Interacting in these ways means one cannot proceed with the story, but they otherwise don't have any effect on the story whatsoever.
Then there are the non-choices of The Stanley Parable. No matter what action the player takes, the story will proceed on a pre-determined track. In the manager's office, you can follow the subtle hints from the Narrator about a keypad's code, encouraging you to unlock a secret door to proceed out of the room. Though if you waste enough time in the office, he'll just activate the override and open the secret door for you to move things along.
Finally, and this can actually apply to all parts of the game, there is the player's choice of whether to interact with the game at all. The Stanley Parable represents choice through the player's own movement through space. This is the basic and most fundamental mechanic of any first person walker. Here it becomes a metaphor for all interactivity in video games. There is always the unspoken choice of any video game -- the choice to interact in the first place. At any point, the player can simply stop moving. In one ending, the Narrator wants Stanley to stop moving and stay in place forever looking at the pretty lights and listening to the new age sound effects presented to the player as a symbol of "contentment." The situation is in direct opposition to the player's desire to interact. Conversely, in another part of the game -- the broom closet -- the game constructs a scenario where the Narrator wants the player to move on from the interior of a broom closet and continue to interact with the world, but the player wants to stay put, thereby choosing to cease to interact.
These are two points where such a situation is given context, but at any point, the player can take their hands off of the mouse and keyboard, leaving Stanley stationary for as long as they wish.The game directly references this in one of the more bizarre endings as the player looks down into the initial room with two doors and a motionless Stanley looking at them. The Narrator goes through his normal lines and soon becomes concerned that Stanley is not moving at all and pleads with him to make a choice. Eventually the Narrator says, "It's okay. I can wait. You need time to decide... I'll wait for you to decide what is the right thing to do. Take as much time as you need." The Stanley Parable will still run and all the possibility space will wait for the player to come back and begin interacting once again.
So often when we talk about choice in video games, we end up discussing narrative context and lamenting the technological limitations of being able to implement true plot altering choices into the narratives that exist in games. The Narrator speaks to this idea directly in various ways through the many different results of The Stanley Parable. But what is often ignored in such discussions is the mechanical essence of making a choice. Choices are presented in such a matter-of-fact manner in games and yet paradoxically are so abstract that the implementation of those choices is left by the wayside. Understanding the importance and meaning of such choices is placed on the playthrough and not on the possibility space that these choices afford. Mass Effect is about the player's "unique" Shepard, and the choices in the game are a means to an end when defining their version of Shepard. It doesn't matter what would happen should the player let the council that Shepard is an agent of in the game should that player chose to save them instead. Because the game is about their Shepard, only the choices that are actually made matter. This is a self defeating prospect, as so many players proved with their response to the ending of Mass Effect 3. They could see that the possibility space and that the choices that they made to define their Shepard (and from which they would derive meaning from) ultimately didn't matter.
In The Stanley Parable, each individual choice is inconsequential. The game will restart soon enough, and the player will make a new set of choices before beginning the cycle all over again and again and again. The player can blatantly see the possibility space laid before them. The options have been given physical form. The mechanics of the choices are made obvious, making the system by which the player enacts a new playthough obvious. In the end, any individual playthrough from beginning to whatever end that the player arrives at is only a part of a greater whole. The meaning is derived not from a single set of choices, but the relationship that all of the choices have to all the others, choices represented through spatial relativity. Video games are good at representing spatial relativity.