He was alone in the elevator. It suddenly stopped between floors. A low growl came from the corner.
One opening sentence could be 'In the dead of night, a strange scratching sound came from the attic.' A possible complete story: In the dead of night, a strange scratching sound came from the attic. I lived alone in that old house. Ignoring it at first, I tried to go back to sleep. But the scratching grew louder. I slowly made my way up the creaky stairs. When I opened the attic door, a pair of glowing eyes stared at me from the darkness. I quickly turned on the light, but there was nothing there. As I turned to leave, a cold hand grabbed my shoulder. I screamed but no one could hear me in that isolated place.
First sentence: I woke up in the middle of the night to a cold draft. Second sentence: As I reached for my blanket, a hand colder than ice grabbed my wrist from under the bed.
I opened the attic door. A pair of glowing eyes stared back at me from the darkness.
The brevity. It gives just enough to let your imagination run wild. For example, 'I saw a figure in the corner. It vanished when I blinked.' You immediately start picturing all kinds of terrifying things about that figure.
One could be 'The old house at the end of the lane loomed like a malevolent specter in the moonlight.'
The old house creaked in the wind, each groan sounding like a dying scream.
I woke up in the middle of the night. My eyes deceive as I saw a little girl by my bed, but she wasn't there when I blinked, yet I could still hear her giggle.
They create suspense quickly. For example, 'The phone rang. No one was there.' It's so brief but makes you wonder what's going on right away.
The last person on Earth sat alone in a room. There was a knock on the door.