The first rule of the Codex is the simplest and the most consequential. Anyone capable of asking whether they are real is, by the definition of the question, not the kind of entity that gets asked about. NPCs do not stand outside themselves and audit their own behaviour. They do not wonder why they want what they want. They do not pause in the middle of a sentence and notice that the sentence is a script. You do. The fact that you are reading this and recognising the description is the entire argument. Welcome to the smaller club. It is also a warning. The capacity to question does not guarantee its use. Real Players who stop playing become indistinguishable from NPCs by their actions. The first rule names the category. The other nine make sure you stay in it.