Fewer words. #8 years later, I still can depend on one
The details of the story itself is where the horror starts ... not in the amazing visuals, but in the simple idea of what is one of the most horrifying things most of us go through, and that is the idea of giving birth ... it fills women with anxiety, and for men, the thought of going through it is a nightmare. Take away the joy of birth and miracle of creation, and distill the process down to the core fear, pain, blood, and anxiety, and you have the origins of this great story. At the reptilian level of our brains, it is virtually impossible to sit through this and not feel a sickly fear.
Visually, this is no rubber suited actor ... this is an actor in a work of art! Giger's macabre masterpiece of design was the no-brainer to win the Oscar, and despite over 30 years having passed, no one has come close to bringing a more horrifying monster to life. Pair this with the darkness, the steam, and confined space, and what little you were shown was the seed from which the nightmare grew in your mind.
Jerry Goldsmith continues a trend of minimalist music that works brilliantly here ... not quite as atonal as his work on "Planet of the Apes". You don't need a sweeping score to aid your emotions this time ... his mood music fits the bill perfectly. While not as appreciated as some of his better known work in "Chinatown", "The Omen", or even "Star Trek: The Motion Picture", Goldsmith's score for Alien is perfect for setting a dark and dreadful mood.
The big surprise in the film isn't the final stinger at the end ... rather it is the gradual elevation of a woman to the role of hero in a horror film. In the beginning, Weaver's Ellen Ripley is the last character to speaker their first lines in the film. At first you think the hero will be the captain (Tom Skerritt) or the intrepid explorer (John Hurt), but not until the crew is whittled down to the sole survivor do you realize it is this woman, scared out of her wits, who will be alive for the final confrontation. It is brilliant, pioneering writing matched with a great performance that does not give away the heroism too soon.
It spawned many, many pretenders, and set a bar so high that with the exception of James Cameron's brilliant sequel, none of the followup films have approached this level of emotion. It is a landmark film within the genre, and overall a classic in the art of film making.