Sure, the movie might date back to in 1979, but somehow, Century FOX has decided to create a whole new trailer that has the look and feel of something released today to promote the blu-ray editions of the movie.
The time is the future. The crew aboard a massive commercial space vehicle is enroute to earth with a load of extraterrestrial ore when they are sidetracked by mysterious signals from a nearby planet. The signals seem to be calls for help and when the space ship arrives they find a ruined, moldering spacecraft and within it egg-like living organisms.
–Alien (Blu-Ray)
–Alien 35th Anniversary Edition, Director’s Cut Blu-ray
They also offered the same treatment to Aliens: