The opening sequence of Insidious effectively sets up the horror genre through various cinematic techniques. It begins with ominous, unsettling music and slow edits that build tension. The abandoned house setting is a horror convention. Red titles representing blood and the smudging effect cause discomfort. Character introductions show an innocent family but hint at a darker element. Mysterious lighting, slow pacing, and an ominous grandfather clock repeating foreshadow its importance to the plot and create an eerie atmosphere. These elements come together to unease the audience and signal this is a horror film.