dudalb
Penultimate Amazing
I suppose THX1138 is too well known to be considered forgotten - at least amongst film nuts, of which I'm pleased to note there are a number here.
But, I find that it's mostly "known" but not seen. Every film geek can recite its pedigree, but very few have ever watched it. And it did horrible box office. It was completely unknown at the time of its release.
A lot of the films mentioned in this thread are too well known to be forgotten.
In the talked about but never seen department, there are an incredible dumber of people who claim to be big fans of the Monster Movie genre, but have never seen King Kong or any of the Classic Universal Monster films. That is like saying you are a fan of English Drama but have not read any Shakespeare.