We’re not going to tell you what The Stanley Parable is, because we can’t. It was a mod for Half-Life originally – now it’s its own thing, a game about an experience, something between philosophy and metaphysics, existentialism and solipsism.
Actually it doesn’t matter what we say about The Stanley Parable because it’s not something you can talk about and even if it was it wouldn’t be the same thing to everyone. It certainly wouldn’t have the same meaning. Hell, maybe it’s not even a game.
Thoroughly confused? Here, maybe this trailer will help. You should really go pick it up on Steam when you’re through watching.