Ridley Scott has made a series of somewhat odd comments about the upcoming sequel to Prometheus, his 2012 quasi-prequel to Alien.
Prometheus 2 is still due to go into production in February 2016 and will see Noomi Rapace and Michael Fassbender reprise their roles as Elizabeth Shaw and the android David. At the end of Prometheus they stole an alien starship and set out to find the homeworld of the Engineers and somehow stop them from destroying Earth. In the meantime, a horrendous and almost-familiar alien creature had come into being on LV-223, although with no food around and no more people or Engineers, presumably its chances for long-term survival are bleak.
Scott had previously said there would be a trilogy of films in this series and the last film would tie in with the original Alien, presumably explaining why the Engineer starship carrying hundreds of facehugger eggs ended up crashed on LV-426, as we see it at the start of Alien. The middle film in the saga would have the fewest connections to the rest of the Aliens universe, focusing as it likely does on the Engineers and their backstory.
Scott doubled down on this last week, confirming that Prometheus 2 would not feature the traditional xenomorph at all (not even in the very brief and ambiguous way the original did in its closing moments) and we'd have to wait until Prometheus 3...or Prometheus 4, although knowing Scott's sense of humour he may have been taking the mickey out of fans with that last statement.
Today, just to confuse everyone further, Scott announced that Prometheus 2 will in fact now be called Alien: Paradise Lost. Erm.
There are several explanations here. The most likely is that Fox has decided it wants to use a brand name to "universify" the Alien franchise in the same way Marvel have with their films and Disney has with Star Wars, with lots of films in the same universe even if some are connected only tangentially. Fox are also developing a new core Alien film with Ripley (Sigourney Weaver) and Hicks (Michael Biehn), to be directed by Neill Blomkamp. Although it has the working title Alien 5, this other film seems likely to jettison Alien 3 and Alien: Resurrection from continuity and pick up instead twenty years or so after the events of Aliens. Some of Blomkamp's concept art for the film shows an Engineer starship being dissected by humans (possibly from the Weyland-Yutani Company), so it might be that Alien 5 and Paradise Lost will yet find a way of tying into one another. Or it might just be a bit of branding, and we may even see the first film retitled Alien: Prometheus for some future re-release.
Some thoughts on how Prometheus and Alien tie into one another can be found here.