Intentional fallacy approach is not the same thing as 'the author is dead'. Intentional fallacy approach is the criticism of analysis of an author's life in an effort to try and find out the 'truth' behind a work of literature. I disagree with this approach- a work of literature should not be seperated from its place in history, which is what occurs when people ignore the writer altogether. 'The author is dead' states that an author's analysis of his own work is no more valid or 'right' than mine, yours, or anyone else's as long as the analysis in question is supported by the novels.
Now, I'm not saying that the author isn't able to shape his own work- he can still write sequels after all. I'm just saying that anything outside of what is in the books is extra information that you can accept or deny. He says there is no proof of Gods in his work- that is a valid opinion, but I respectfully disagree.
Except there's a flaw in your argument here: most of what's created in the mod is based on evidence supplied by the author, quite often evidence supplied by direct emails or discussions with GRRM (such as, who's homosexual). The author's intentions are considered final word here, simply because in the construction of this mod, flubbing those details would dramatically shift large parts of the mod; and then you wouldn't have "A Game of Thrones Mod", you'd have "A Mod
Inspired by A Game of Thrones". And it wouldn't be the same.
Second, there's no textual evidence that definitively proves the existence of any gods in the books. Visions, prophecies, answered prayers, etc.; these can all be conjecture or self-deception or triggered in various other manners. Just as in the real world, people have visions of saints and angels and Jesus and god, so too in Westeros and its world do people have odd visions. In the real world, we don't necessarily always accept whatever visions people claim to have (though certainly, we occasionally do).
If you go, "but the magic!" well, that's not really definitive evidence. From the text of the books, magic is incredibly strengthened with the appearance of the dragons; which would seem to suggest that Dany is the source of magic, in which case, well, there, you can play as a god by playing as the Targaryens. If there are gods, why did the Old Gods allow their weirwoods to be cut down? Why did the Seven allow Melisandre to burn them? What about the plurality of death-worship in the halls of the Faceless Ones? Who made the Others? There's no more proof of the existence of Gods in
A Song of Ice and Fire than there is the real world. It's all faith. Any thoughts or commands or actions or inaction attributed to them is just as much conjecture here as it is in the real world.
And finally, that brings me to the last and probably most important point: modding in the ability to play as gods changes the mod entirely. You're not talking about a Crusader Kings 2 mod. You're talking about a completely different game. It sounds more like the Sims than Crusader Kings. In fact, there are plenty of simulation/god games for you to mod which would more easily lend themselves to that kind of style of play.
If you mod in the existence of gods, and someone decides to play as a regular house, now it becomes completely pointless, when R'Hollor can just immolate your people on will. So a large part of the game: playing as families (indeed, the whole basic mechanic of the game that you are a dynasty) becomes completely foolish.
And if you're really insistent on playing as a god; I have one suggestion for you: cheat.
