Horror is not so cut and dry
When asked what my personal games are like, I always say: "The reality of war."
This typically leads to stunned silence and then questions how horror, the occult, and the supernatural fit in.
For the most part, they don't.
Yes, there might be a ghoul here or a witch who raises the dead, but for 90% of the time, the characters my players play are your average everyday colonists with little time for Freemason intrigues or spending time in their forge making soap. There is a war to be fought.
The characters my players created are an interesting mix.
David and Henry are dealing with hiding their homosexuality, from not just the world at large, but with their immediate circle of friends.
Beatrice's character is dealing with her identity. Originally hiding the fact she was a woman, she enlisted as a man, and now she is questioning is this her true self.
Patty is playing a pastor who joined to fight for freedom but is now conflicted with the breaking of the commandment "Thou shall not kill."
Finally, there is Sean whose character is a Pequot and secretly close to insane (he asked me privately if he could start the game with only half of his starting Sanity). This insanity is due to the horrors he has seen in the endless wars he has fought. These wars include not just the French and Indian War, but also the various tribal fighting that took place along the frontier.
Not one of these characters is "magical" or experienced with the supernatural. The characters the players have played (many have died, this is war after all) have seen a few things (total of 20 since the game started way back in 2007) falling into that category. Why? There is a war on and war has no time or place for anything else.
For me, the Sanity rules come into play with the situations the players find themselves in. These situations deal with not just their backgrounds but their endless fighting and hardships. This chips away at not just their sanity but them losing a little bit of themselves as they face hardships.
When I read stories like the one linked here, it gives more fooder for my personal game. It also helps my players (one of which sent me the link before I sent it to them) in the playing their characters.
When you run your own games take a moment to think about the type of game you want to play. Every rule is able to be shaped and utilized to support your ideas. From the gritty and grounded game I run to the full supernatural occult game Patty (I love it when it is her time to run a game) runs the rules are there to aid you.
As I write many times, the Rulebook is your toolbox.With these tools, you are free to create your game. Use them and take what you will from the history of the setting. You, and your players, might be surprised by what you create.