The author of The Stanley Parable says that “it’s actually best if you don’t know anything about it before you play it.” And that’s probably true. So if you like, you can play it before continuing.
While we’re waiting, a bit of background: The Stanley Parable is a game by Davey Wreden made in the Source Engine. It requires some form of the Source 2007 engine to play, which you have if you own Half-Life 2.
The Stanley Parable, for all its exploration of interactivity and choice and video games, isn’t actually interactive at all when you get right down to it. Yes, it has six endings and branching and all that. But as with many games with multiple endings, as soon as you tell the player that they exist, she wants to view them all. And especially with Stanley‘s left-or-right, red-or-blue choice structure, trying out the choices exhaustively is trivial.