I wouldn't be very happy if you took the whole thing, slapped some changes on top of it and made a separate mod out of it. But you're free to borrow as much stuff as you want unless you shamelessly clone make a modification on top of it and call it yours .
And if you mean that you want to mod it to your taste and share with people, why not. Someone may like it that way.
I just didn't get this part:
more subtle and "serious" theme
What "unserious" is here? I have no flying spaghetti monsters and burning socks, or do you mean something else?
There's a reason why I put "serious" in quotation marks: it's not a very good term to use.
What I mean was that this is sort of too all-encompassing, I prefer stuff which has more limited content and makes one use his imagination. It's like when you put so much "magical" stuff into a fantasy world, it sort of takes the magic out of it. If "magic" is ever anything but rare and extraordinary, defying the belief of both those in the book and those reading it, it becomes no more miraculous to behold than gravity. And so, what I would do is to try and make most of what's been changed in the game the exception instead of the rule. The players, being already used to a "normal" game, will at first see little difference, and therefore will quickly get settled down into a comfortable routine, and whenever something new happens they will experience it, and then get over the excitement just in time for the next new thing. And if I wanted include a different theme, I'd change
everything to match. This would mean that I'd have a different mod for each different culture and each different time period I wish to mod in, but there would be
NO bridges linking any two of them: each would be independent of the others.
As for what I'd like to do with
your mod, I'd like to just take what I like and drop what I don't and then use that as a basis for my mod (with credits to you, of course). In many spots I'll probably just take your
concepts and utilized them in what I think would be a better way.