The Stanely Parable (referring to the first game) was largely about this notion of author versus audience--who is actually in control of a story when it's told? Each ending in the Stanley Parable explored different ways of resolving the power struggle--does the Narrator have power over Stanley? (Countdown, Mariella, Apartment, Freedom endings) Or does Stanley have power over the Narrator? (Wrong Choice, Zending, Not Stanley, Games)? Or maybe it's the player who has ultimate control? Or the game designer? The Stanley Parable was "about itself", but really the deeper themes I think are about the form and structure of narrative, and how narrative control is a type of power.
(also I've decided that the Homestuck Epilogues are just a worse version of the Stanley Parable, sorry everyone.)
The Stanley Parable: Ultra Deluxe (referring to the second game as a whole) is also about itself, and the Stanley Parable, but is more generally about ideas of nostalgia, seq