Alan Wake Theory
I'm pretty sure this is a theory that's already known, but I wanted to share my view of it anyway.
I think the games point toward Thomas Zane being the overall writer/filmmaker/creator of the Alan Wake story. Furthermore, I believe that in 1970, when Zane got stuck in the Dark Place, he began either writing or making a movie that would eventually free him from there. That movie/writing is what the Alan Wake games are.
This would explain why Zane and Alan are identical and why it's mentioned in the games that Zane made a movie where he was starring as Alan Wake, and everyone else in the games was starring as the characters they are.
It's not Alan writing Initation or Return in hopes of getting himself out of the Dark Place; it's actually Zane acting or writing as the CHARACTER Alan Wake in what he believes is a storyline that will eventually free him from the Dark Place. Alan Wake doesn't know this because he's just a character in the story, so even though it's Zane playing him, he himself believes that he's simply Alan Wake, just like Alex Casey believed that he was simply Alex Casey.
I get it probably sounds complicated or badly explained, but I hope it at least makes a little sense!
EDIT: I forgot to add that it would also make sense why the Anderson brothers call Alan "Tom", because they exist outside the story due to their powers and cannot be tricked by it. So they would know that it's Tom playing Alan all along.
EDIT 2: Also another thing I forgot to add, the theory would explain the manuscript pages that Zane wrote describing Alan as a child and his mother giving him the clicker, since the clicker originally came from Zane's lamp. So he literally wrote it into existence while Alan was still a kid, and because he also has to obey the rules of the Dark Place, he'd have to make the story/play be believable, so he couldn't just spawn in an adult man to come save him. He had to write Alan from the beginning, and that's why it has taken 50 years so far.