Me too, though I'm bit a behind seeing here in Holland we just had the season 1 finale. That said I have never cared about spoilers, heck I knew about Snape working for and killing Dumbledore long before I even held a copy of the Hlafblood Prince without caring about it.

I'd be interested in helping GM-ing this if you'd like. Also, I'd like to bring up something in relation to this. How are we going to fit into Gravity falls? Will we be taking control of preexisting characters, or be making our own to solve the mysteries of the town?

What about having our own mysterious town somewhere in the northwest? It can have as many similarities to Gravity falls as we want, locations, characters, and history, but there's still so much that we don't know about the town and the people there, so there could be a big game changer in an upcoming episode that could throw everything off track. Not to mention, we would be able to do whatever we want to and with the town without being incorrect to the show.

Couldn't we possibly all be friends of who are related to each other in a way, the government attempting to find the place of supernatural beings while most of us don't know whats going on except for one. The group of players find a book as they venture in the forest and attempt to depuzzle it, thus we then follow the episodes or we take on our own path.