Yeah, Xeno could be right. I've been saying it's possible that closer to the release, the film's title *could* actually be changed to "Alien: Prometheus", or something. It does make sense that Ridley would keep it hush hush.... when the trailers for the film come out, there could be a lot of buzz when it comes clear it IS an Alien film.... there might be more of a rush and a "panic" of people wanting to see it (which is a good thing come opening day). If he came out and said it's an Alien film all a long, there would be so much interest in the film that likely most of it could be leaked out, and also come opening day, it's possible the film would be old news, or people would just be bored of it already. This way we have a lot shorter of a time period to know what's actually going on.... and way more of an excitement when we find out.
Then again, I'm just speculating, and I do think it could go either way.
Any news on if Giger is involved in this movie? Kind of a bummer if he's not.