I've often heard that the 1998 Kurt Russell film Soldier is meant to take place in the Blade Runner universe; they have screenwriter David Peoples in common, and there are some Easter egg references to BR backstory elements. I don't think I ever saw it, though, and apparently it has a poor reputation.
I saw it once, decades ago. As I recall, Peoples threw in a reference or two, with the idea that the main character has been at one or two of the battles Roy Batty refers to. It wasn't a classic movie, more what you'd have rented at Blockbuster if you got there late and all the good stuff was already rented. Which is probably how I saw it.
Alien wasn't created by Ridley Scott?
I know Blade Runner was based on the Phillip K. Dick book, but he does seem to be the one in controlling the movies.
Dan O'Bannon wrote Alien from a story developed by O'Bannon and Ronald Shusett.