The Stanley Parable is an interactive walking game where the player is narrated as they navigate the game. More a comment on the state of modern gaming than a full fledged game itself. An experience if you will, with fictional story elements and some small parts of interactivity.
Pro Discusses the illusion of choice in games
One of the main themes of the game is the illusion of choice that's presented in games. While a player can make a vast number of decisions in the game, the narrator reminds the player he can only make decisions that the game allows him to and how the game manipulates the player into making them. The narrator points out that not just common choices such as what path to take to get from point A to point B, how to approach a certain situation or what ethical choices are available are limited to the game's designers having thought of and implemented those aspects of the game, but decisions such as purposeful suicide, not taking action, disobeying instructions and even turning off the game are only there if the game allows them to be there.
Pro Points out narrative limitations in games by encouraging breaking narrative structure through gameplay
The game encourages players to explore decisions that would change the meaning of the presented story. What if you took a left turn where the game asked you to take a right? What if you decided not to push a big red button needed to continue playing because you didn't agree with pushing the big red button? What if you died in a boss battle? How would that affect the narrative of the game?
The game rewards you for not following the "intended" narrative structure of the situation in order to point out how the structure is unavoidable in games as a whole. The process of attempting to break the structure can be highly satisfying in The Stanley Parable and can help you better notice limitations of narrative in other games.
Pro Insightful commentary on state of game design
The game tackles topics such as ludonarrative dissonance, choice in games, narrative limitations, etc while mostly focusing on the relationship between the game and the player in terms of storytelling in a very meaningful, educated and entertaining way.
Pro Exceptional narration
Excellently crafted, hilarious writing delivered by a well spoken, charismatic British narrator. Kevan Brighting has become somewhat of a cult success since the game due to its cult like status which just shows how deserving he is due to how well done the narration of the game is done.