There’s the Prometheus continuity that divided many fans of the series, the various video game sub-franchises that have focused on different characters, the Alien vs. Predator series (which has its own B-movie charm), and the ill-fated production of Alien 5, which would’ve seen District 9 director Neill Blomkamp take control of the series.
It will be interesting to see how these Alien short films flesh out the mythology of the series, because it has splintered off in a wide variety of different directions over the years.
There are a lot of avenues to take these stories, along with plenty of potential for brand new stories, so we will have to see what these creators come up with.