It has an incredibly tortuous history, particularly the script. The first draft was written by William Gibson (Neuromancer) and Ripley spends the film basically in a coma. The second draft had no Ripley & involved a colony of farmers. Then it became a prison colony & Ripley was back. Then it was on a monastry. Then Ripley was to be killed off and this version is worth expanding on (interview with David Fincher who ended up directing it):
FINCHER : In the draft Larry
was writing, she was going to be this woman who had fallen from the stars. In the end, she dies, and there are seven of the monks left --- seven dwarfs.
Q : You're kidding?
FINCHER : Seriously. I swear to God. She was like...what's her name in Peter Pan? She was like Wendy. And she would make up these stories. And in the end, there were these seven dwarfs left, and there was this fucking tube they put her in, and they were waiting for Prince Charming to come wake her up. So that was one of the endings we had for this movie. You can imagine what Joe Roth said when he heard this. "What?! What are they doing over there?! What the fuck is going on?!"
A few more screenwriters later & it was back on a prison with Ripley. David Fincher did his best, but the studio got heavily involved and he now disowns the film (although I don't know what he thinks of the so-called "Special Assembly" cut - http://www.imdb.com/title/tt0103644/alternateversions )