Alien: Covenant will star Michael Fassbender and Noomi Rapace (the only two cast members currently listed on IMDB), and is being written by Michael Green and Jack Paglen.
The film will be fifth in the Alien franchise if you go only by title, following Alien (1979), Aliens (1986), Alien 3 (1992), Alien: Resurrection, or the sixth film if you include Prometheus (2012).