Horror is a broad genre with many different sub-genres spawning from it. Considering that fear is entirely subjective and there are billions of people on this planet all scared by different things, constructing a #horror film that engrosses a significant portion of the potential audience is a difficult task. The simple fact is that there is no specific filmmaking technique that will automatically guarantee that your film will be scary.
Audiences gravitate towards different aspects of horror at all times: gore, comedy, body horror, realism, surrealism, existentialism, claustrophobia, sexuality, paranoia, etc. There is, however, an element that all successful horror films universally share. One could realistically define it as the one ingredient necessary for a good horror movie.
It makes sense, doesn't it? If you want an audience to feel scared of something within the diegesis of your film, you have to immerse them within the world of said film. When the audience member's first reaction is to immediately detach from what is happening onscreen, you've failed as a horror filmmaker, regardless of what techniques you've employed in crafting your film.
Let's have a look at some examples of what I am talking about:
This is the opening to Halloween (dir. John Carpenter, 1978). It's iconic due to how effectively it sets the suspenseful atmosphere of the rest of the film. What makes this sequence so effective? The notion that we, as the audience, are about to commit a horrific act of violence through the POV of the killer. What does this achieve though? The answer to that is fairly simple: It makes us ask questions.
What motivates us as the killer? Is there an inherent sexual frustration that manifests in the act of violence we commit on Michael's sexually active sister? Is there a familial jealousy, as we are left home alone on Halloween night with nobody to keep us company? Is it an act that is done in haste, only committed because wearing a mask allows us to disassociate from what is going on onscreen? Or, is it nothing psychological at all, and we are just inherently evil and want to punish those around us?
The thing is, the answer to this question is not important. Ultimately, Michael Myers's motivation is kept ambiguous because we are not witnessing his story play out. Instead, we are seeing the prologue for what is ultimately the tale of Laurie Strode. Yet, Carpenter's staging of the opening scene has forced us to participate by making us hypothesize what motivates the killer's actions.
The brilliance of this is that our hypothesis then proceeds to carry on throughout the film, as we then determine what exactly it is Laurie is trying to fight off. Is her attacker a faceless representation of male sexuality? An extension of her tendency to isolate herself from her peers? Is it simply the manifestation of pure evil — the antithesis of her pure self? The movie asks us to make those conclusions, thus ensuring our participation.
What about this scene from 28 Days Later (dir. Danny Boyle, 2002)? Superficially, it's a great gore scene, as we watch Selene hack the arm off her companion who she suspects is infected. But what makes this scene really chilling are the questions it raises. We don't know whether Mark was infected or not. The wound doesn't necessarily resemble a bite or a scratch, and he didn't show any signs of turning into one of the rage-zombies when Selene turned her weapon on him.
Surely, Selene is justified in her act, as the alternative would be giving him the opportunity to turn and kill them, but this is where the audience is then asked to participate once again. Do we trust Selene? Should we trust Selene? Jim does, but should we trust his judgement? Could it be that Selene is so unhinged and so determined to survive that she will kill Jim at the first opportunity? If Jim does end up being a liability — having just come out of a coma — should he die? Sure, it might be difficult for us, as he is our audience surrogate and we sympathize with him, but perhaps his death may be necessary for the greater good.
Once again, the gore may be there, but it's the context around the gore that makes us as audience members part of the scene, making it all the more enjoyable.
I think the definitive example of this is the early work of director George A. Romero, particularly my favorite film of his: Day of the Dead (dir. George Romero, 1985). One could argue that there's nothing really scary about this scene is there? It's brightly lit, there's no blood or gore, and the only conceivable threat is chained up and appears relatively docile, right?
So what is the purpose of this confrontation? Is Romero trying to say that humanity is doomed because, no matter what our conditioning, our first instinct is to respond to a potential aggressor with aggression of our own? Is Captain Rhodes's assumption correct in assuming that Logan is merely wasting his time by trying to domesticate the enemy, or is Logan's display of empathy the only glimmer of hope in a bleak and nihilistic world?
Suddenly, the futility of everybody's actions becomes apparent. There aren't enough bullets to kill all the zombies, but there isn't enough time and resources to try and take a more peaceful option, either. We're basically watching the dregs of society barely scraping for survival in a world that's going to consume them at any minute.
Theoretically, this scene shouldn't be scary at all, yet Romero gives us the tools to make it scary through the craft of filmmaking, and all it involves is making us a part of the world that the characters inhabit. No need for darkness, gore, violence or jump scares.
Bad horror movies fail because, as much as they try to gross out and startle the audience, they fail to recognize that an audience needs to feel involved in what's happening onscreen. Audience participation is the key to a good horror film, and while a movie doesn't have to employ methods as elaborate as the three I mentioned previously, there still needs to be something there that the audience can latch onto.
What do you think are the most important elements of a horror movie?