Four dollars! In 1979?! That seems really high. OK, maybe I’m comparing it to when I saw a lot of pictures in college nearly a decade later, but then on bargain Tuesday, or college appreciation Wednesday, $4 would get two people in.
On the other hand, Alien in 70 mm projection would have been pretty cool.
Knowing what I do about the movie now, there is no way that I would encourage someone under 18 to go see it. Some quite disturbing imagery in there. (Did you hear how the chestburster scene is, to an extent, enforced method acting? The actors did not know just how bursty it was going to be beforehand.) But, the movie poster is classically minimalist, and newspaper summaries/reviews of it at the time probably did not offer that much guidance.