He Knows You're Alone seemed to come pretty early in the 80's slasher boom, so it hues closer to Halloween than, say, Friday the 13th in the gore department. It fancies character development and suspense over cheesy effects and severed limbs flying everywhere and it's all the better for it.
Despite a silly detective subplot that feels unneeded (if we're being honest, most detective subplots in these kinds of movies are unneeded), He Knows You're Alone is a fairly well paced and suspenseful slasher film centering around Amy, a bride to be with cold feet, who's being stalked by a mysterious man. She sees him at the bridal store, ice cream shop, outside her window, and even in a carnival haunted house. He's definitely been taking a few pages from the Michael Myers playbook, because he's taking his sweet time to get to her by disposing of her friends and loved ones first, all the while a slightly familiar piano/synth theme plays.
This movie is mostly known for being the breakthrough film of Tom Hanks these days, but He Knows You're Alone stands quite well on its own two legs as a somewhat scary example of a slasher movie. It has its pacing issues here and there, but the characters are well drawn for a film of this type and that just adds to the suspense.
