Some other scary two - sentence stories could be. 'The cemetery at midnight was still. But then the tombstones started to tremble.' 'I was alone in the old library. Suddenly, a book flew off the shelf and landed at my feet.'
Two-sentence horror stories can be quite scary. They often use simplicity and ambiguity to let your imagination run wild, which can make the fear more intense.
The brevity. With just two sentences, they create a sense of mystery and unease. There's not enough space to fully explain what's going on, leaving a lot to the imagination.
They often rely on the unexpected. Like 'The painting on the wall changed. It showed my future death.' The sudden and strange event in the first sentence is then made even more disturbing by the second sentence. This makes the reader's mind race with questions and a feeling of dread.