Here's why:
* Dark and macabre themes: The story revolves around revenge, murder, and the psychological torment of the victim.
* Setting: The story takes place in a dark, decaying cellar, a classic Gothic setting.
* Atmosphere of suspense and dread: Poe expertly builds suspense through the narrator's chillingly calm demeanor and the escalating sense of danger as the story progresses.
* Supernatural elements: While not explicit, the story hints at the supernatural through the theme of revenge from beyond the grave.
Although there are elements of mystery and psychological thriller, the dominant genre is Gothic Horror.