So, I've got the freebie PDF of MF, and am thinking about picking up the hardcover and some supplements to start up a game based on an idea I've had for a HPL Mythos-inspired apocalypse.
The essential ideas are that the stars go right. The old ones rise, and the world burns. Generations later, after the "God War" humanity is crawling out of the caves, and repopulating the earth. Most of the Old Ones have fled back to be resorbed into Azathoth, but remnants remain. Protoshoggoth DNA hidden in certain lineages have resulted in bizarre mutations.
I'm curious, aside from the core book, and the "Realms of Crawling Chaos" book, is there anything else I should think about picking up? Hardcopies are preferred, and anything available through Lulu, DriveThruRPG, or whatever is fine. Links would be great if you've got 'em.
Thanks!