There's been a lot of back-and-forth from the Prometheus camp about whether Ridley Scott's big summer sci-fi flick is a forerunner to the first facehugger/chestburster chapter. Writer Damon Lindelof wants to clear it all by defining, for us and for himself, precisely what he thinks a prequel is.
The thing about a prequel is, as fascinating as it may to watch Anakin turn to the dark side of the Force, there's an inevitability to it. You know when you go in the prequel can only cover A to Y and then Z is gonna be the preexisting material. You can't end it in an exciting or surprising way. You can only end it in the inevitable way. ...
When I went to go see The Thing prequel, for example, I'm assuming this movie is going to be the sequence of events that led up to a dog being infected by the Thing and then being chased by a helicopter across the frozen tundra—because I know then what happens next because I saw The Thing. And that's exactly what it was. On a certain level, you're satisfied because if you're calling a movie a prequel, that's what you're expecting. On another level, you sort of walk out going, "Boy I wish there was a little bit more room for me to not exactly know what I was walking into."
In my opinion, in order to define Prometheus as a prequel, Is it set in the Alien universe? ... If you just watch the teaser trailer, and you see how the word Prometheus reveals itself ... or look at the production design, you don't need me to tell you anything.
So then the next question is: Is it a prequel to Alien? To that, I can't really answer the question because my definition of prequel, the A-to-Y definition, I hope it's not. I hope that this movie can be surprising. The ending of this movie; the sequel to Prometheus is not Alien. The sequel to Prometheus, if it does well and people like it, would be another movie that goes off in its own direction, that runs tangential to Alien.
It's worth listening to all 90-some-odd minutes to hear Lindelof describe the "thanks for making Lost with me" presents J.J. Abrams got him and to defend his youthful belief that Blade Runner was, in fact, a sequel to Alien.