Quote Originally Posted by Jacky720 View Post
Every door is rigged with runes that do something other than explode you. It fits neatly into forming a passcode, if the something is "track which door you entered".

Which isn't really evidence because of all the other interpretations, but it does fit.
In the abstract, it is a fine idea.

Concretely speaking, it does not fit in this story, because the doors are so perfectly unidentifiable. If the doors had unique names or numbers on them, I could imagine there is a puzzle to be solved, such as you suggest. But The Giant would have dropped hints well before this point in the story.

Call the Chekow's Anti-Gun. When no mention of a gun has occurred in the story, you can't have a hidden gun pulled out from behind some books on the shelf in the third act, and used to immediately kill an important character.