Originally designed as an open world/sandbox game, but was changed to be a more linear experience for better pacing.
When a pirated copy of this game is played, Alan is constantly wearing an eyepatch and a message appears that the player should buy an original copy. Apart from that, it has no disruptive effects on the gameplay itself.
Title character Alan Wake wrote a successful series of books about Alex Casey. This parallels Remedy's previous series Max Payne (2001). Both are hard-boiled New York detectives. Several Alex Casey book titles (in Wake's office bookshelf) match titles of Max Payne chapters. Sheriff Breaker mentions the Casey books were a bit heavy on the metaphors, a common critique of Max Payne. Finally, the actor who voiced Max Payne reads Alex Casey's narration.
If you watch the "Harry Garret Show" to completion, Harry will ask guest Sam Lake to "Do the face again" before the show ends. The "face" Sam is making is the face of Max Payne. The video game, Max Payne (2001) was previously developed by Remedy and Sam Lake's face was digitized and used for the lead character Max in the very first Max Payne game.
A live-action web series called Bright Falls was made to promote Alan Wake before its release. Bright Falls features many of the characters & locations that are in Alan Wake, and is about a man turning into a taken which are the main enemies of the game.