A lot of horrors make up the Shadows over Vathak, from the long-buried Nosferatu Kings to the all-too-human Great Cleansing. But predating these other terrors and perhaps the world of Antikthon itself, the Old Ones are the most obvious vector of cosmic horror in Vathak.
Cosmic horror, well, reminds me of this guy I saw a few times at Origins:
And there's something to be said for face tentacles and impossible wings, but your game with Cthulhu can be post-apocalyptic or mecha combat... it can even be a children's tale or a love comedy. What makes it cosmic horror in particular, even if we wipe away the traditional names?
- "Now all my tales are based on the fundamental premise that common human laws and interests and emotions have no validity or significance in the vast cosmos-at-large." - H.P. Lovecraft
Cosmic horror is some pretty heavy stuff and, frankly, it's something we should consider seriously before deploying at the gaming table. A lot of us play RPGs to escape the terrors of life in a universe that seems, at best, fundamentally uncaring. Dragging players through that can be incredibly cathartic or incredibly frustrating, so we should always make sure everyone's excited before jumping in the deep end.
There's nothing wrong with using the trappings of cosmic horror to support another theme. Eldritch horrors can stand in for the casual cruelty of society or the cold machines of war when we don't want to deal with them directly. They're also just cool. C'mon, look at that Cthulhu!
But, when we do want cosmic horror, I feel our role as GMs and players changes a bit. In a lot of Pathfinder games and particularly when using a published adventure, the cosmos-at-large is structured around the players' needs and interests. It keeps prep down and helps make sure the game is engaging and entertaining to everyone involved. But it means the PCs are the most important people in the world and are therefore immune to cosmic horror's "Total Perspective Vortex."
Creating a universe that can exist beyond the players' desires and feels like it will keep moving without them is a lot of work, which is one of the reasons Vathak exists. It can be as cold and uncaring as you need it to be, it's just a question of setting the thing into motion.
And playing in cosmic horror, to me at least, boils down to the question "even though I know the universe is uncaring, what does my character believe in anyway?" It's hard to expose that motivation to the indifferent world and potential consequences, but in a universe of cosmic horror, literally nothing else matters.
GMing and playing in cosmic horror games aren't easy questions and they deserve more attention than the few paragraphs they're getting here. But the universe doesn't care and next week, we'll be talking about another thread of horror that's important to Vathak.