I've gathered that making up new monsters, tomes, and cults is not unheard of among CoC roleplaying, but what about deities? Is it okay to invent, for the purposes of a specific game, a new Outer God or Great Old One? Or would that be considered in bad taste?
I know I've come late to the Lovecraft party, but after studying the history of the mythos for a bit, it seems that everyone's invited as long as they bring heaping helpings of MADNESS and DOOM. I don't see why people can't throw more contradictions into the already-confused mythos potluck so long GM's "don't negate" the mythos (i.e. "Actually, Azazoth is a pussy; this thing is really scary!"). In fact, I feel that new creations become necessary for real horror to occur in a CoC game once you've read the stories/sourcebook. As Ross once told me, it is harder to be creeped out in game when that player voice in the back of your head is screaming, "Oh, that shit is definitely a Star Vampire. Buy a plane ticket and get the hell out of town. Game Over." Having versed myself more, CoC gaming seems to be moving towards the tactical decision of when to die/go crazy and away from the more character-driven logic of "OMG! WTF is that?! AHHHHH!" that I feel was Lovecraft's, and the system's, original vision.
But looking at the GenCon boards, I don't see much in the descriptions promising "new terrors from beyond time and space." Even DG, which adds an interesting new take on human reaction to arcane horrors, seems to treat the deities of the mythos as if they were literally sacrosanct. I haven't heard of any publications expressly dedicated towards the publishing of new mythos deities for the game world. My limited experience in gaming makes me suspect this might not go over well in mixed company, which I suppose is understandable. The CoC gaming system is so powerful in part because it originated organically from fiction; perhaps that tradition should be honored. And who wants another of Dereleth's pansy-ass Elder Gods prancing around? Nobody yearns to hear their GM spout off about how the new guy is "like Hephaestus...WITH TENTACLES!" Yawn.
I mean, if players wanted to live in their GM's personal horror mythos rather than Lovecraft's, they could have played another game, right? In short, my reading of Chaosium doesn't inspire the same eagerness to experiment as, say, Eclipse Phase does, where the GM section is basically, "Maybe the rogue AI's were cuddly and didn't really kill everyone. Who knows? Run with it!"
So I suppose I'm torn on the issue myself. What do you guys think? At what level of the mythos hierarchy should gamers say no more and leave it Lovecraft?
P.S. I'm totally going to try and come up with some new Outer God, regardless of what is said here and/or my massive potential for failure. I'm just curious as to what everybody else thinks.