I wasn't even remotely old enough to go and see Alien when it first came out, although I do remember seeing the image of the big chap sat on his chair with a hole in his chest, in the alien spacecraft, shown as part of a review of the film in ETI (Electronics Today International).
A few years later one of the computing magazines had a program for the BBC Micro, which redefined the colours in one of the graphics modes to create an "animated" image similar to some of the initial footage in the film, that shows the Nostromo's flight path as it lands on the planet.
Even though the technology of the film was appropriately futuristic for 1979, by modern standards it all looks rather quaint. Modern video games can trivially produce far superior graphics. The weapons, computers, medical and engineering technology they use just isn't realistically superior enough for a culture which appears to have extensive and widespread spaceflight.
I'm not sure when I first saw the film, but it was probably on the TV some years later. I don't recall ever having a copy of VHS (for the few years I had a VCR), but bought the box set of all four current films on DVD a few years back.