True horror establishes its hopelessness on the foundation of intelligence.
No one really feels for the C-cup sorority girl investigating creepy noises in her family's Civil War farmhouse basement... with a candle... in her underwear... by herself... in a storm... when the power's out.
That's the entertaining side, the 'tails' side of the Horror Genre coin: scary - but stupid - fun. Suspense & shock - but with stupidity. We roll our eyes & chuckle at what happens - hideous though it may be.
Now consider Ridley Scott's Alien. That crew didn't make any stupid decisions - and still they suffered horribly. Even at the end, after all that loss of life & their ship, all they resolved was one pod of the many that Kane saw.
That is both unsettling and not forgotten by the subconscious.
Solid horror movies end their narrative with resolution, but not with hope.
So, Ripley escapes & we have resolution, but where's the silver lining? The whole movie was about a crew’s inability to deal with one hatched pod. By extension, is the viewer not being told humanity is helpless & will be lucky to escape with their lives?
Some more examples: The Exorcist. Regan's problem was resolved, but the unstated component - that the demon was never killed & roams about freely still - follows long after the stop button.
Halloween. Michael Myers was shot - resolution. But he wasn't dead. The threat of hopelessness begins to emerge. Why was he not dead? Where did he go? Is he coming back? Can I stop him if he does?
Despite Laurie’s intelligence, all she did was buy herself some time. Time that would be plagued with doubt, dread & fear of shadows.
Such questions are the extra step true horror takes. It gives resolution, but undermines it with lingering doubt, unanswered questions, threat, dread and menace.
Alien, Exorcist, Halloween, Texas Chainsaw Massacre - are these stories really over?
No, not the is-there-a-sequel-coming kind of 'over'; Is the tale of this Horror really done? Does this resolution have finality - true Horror forces us to contemplate the answer: "No, it isn't."