I consider it the atmosphere and the way you actually must feel!

Rating: 10/10 (3 November 2017)

In "Alien" we follow a seven man crew en-route to earth on board the huge space freighter "Nostrum". The crew is in cryosurgery, but the on board computer interrupts the journey when a foreign radio signal is picked up. It originates from an uninhabited planet and the crew lands to investigate. There they make contact with an alien life- form...
What makes Alien so great is the constant feel of uneasiness. Right from the beginning you have a feeling that something is wrong. The crew is not particularly friendly towards each other, and you truly feel all the in-group tension. The ship itself is a huge worn out industrial-style maze of halls and corridors, and it feels more like a prison than a place to live. It is as if not only the alien but also the ship itself is against the humans. The Alien itself is the scariest monster in history because it is a ruthless, soul-less parasite completely devoid of any human or civilized traits. The design of the monster is a stroke of genius.
Sure it has a humanoid form, but it has no facial traits or anything else which could give away emotions or intentions. Its actions reveals no weaknesses nor civilized intelligence.
The Alien is more or less the opposite of everything human and civilized, plus the creature is more well-adapted to the inhumane interior of the ship than the humans who build it.
To sum up, you then have a setting where the humans are caught in a web of in-group tensions, an inhospitable ship and the perfect killer which thrives in the ships intestines. You almost get the feel that the humans are the ones who are alienated to each other and to their own ship.