What is to be said about a movie that frightened me back in 70s and still can do so today? I'll get straight to the point of why this movie worked so perfectly, whereas the sequels (the exception being Aliens) did not. You actually get to know, and to like the characters. Director Ridley Scott allows you to get acquainted with the 7 crewmembers. We get to see them carry on conversations and interact with each other for nearly 40 minutes. We see them awaken, eat, and work together. We see humor and tension as they socialize. Then we see them exterminated one by one by a barely-seen presence known as the Alien. We see the pain and hear the dying gasps of Kane who unwillingly became the alien host. We see Brett helplessly carried away into a ventilation shaft, and Dallas without a chance to react in a dark narrow airvent. We see Ash the robot betray the crew with their very lives on a heartless Company order. We see Parker beg Lambert to get away as he sacrifices himself. We hear Lambert cry and scream in shock and pain. We hold our breath with Ripley as she trembles at the sight of the Alien in her shuttle. All of this works not only because we know and like this cast of characters but because we only see glimpses of the Alien, a biomechanical design out of the psyche of H.R. Giger. Ridley Scott was smart to only show glimpses of the nightmarish creature. It leaves the audience with a gaping void left to the imagination. Add the beautiful, eerie music by Jerry Goldsmith, along with a great screenplay and you've got the perfect formula for a classic horror sci-fi movie that has held its own for 20 years and will continue to do so.