There are countless examples of cult movies that changed in the making, and ended up being better for it. Jeff Bridges reckons 2008’s Iron Man, the movie that launched the Marvel superhero megaverse, began shooting without any script whatsoever. Steven Spielberg’s Jaws was retooled as a Hitchcockian suspense thriller, rather than a monster movie exploitation flick, because the director was forced to admit halfway through filming that the mechanical shark doubling for a real great white looked faker than a $3 bill.

But at least these movies had a reasonable sense of identity from the beginning. Iron Man, even if much of the dialogue was improvised on set by Downey Jr and Bridges, always knew it wanted to be a superhero movie about a billionaire in a supercharged tin can. Jaws was always going to be a fishy disaster flick.

By contrast, Ridley Scott’s Alien: Covenant doesn’t appear to be entirely sure what kind of movie it wants to be, even though the veteran film-maker began shooting in April.

For the record, here are the various permutations the film has gone through since it was first mentioned by Scott in March 2012. Back then, we thought we were getting a direct sequel to Prometheus, perhaps with screenwriter Damon Lindelof being duct-taped to a typewriter and forced to explain away some of the original movie’s gaping, incomprehensible plot holes. Later that year, Lindelof conveniently stepped aside, after admitting the sequel might “benefit from a fresh voice or a fresh take or a fresh thought” (perhaps in the same way that Lost really ought to have brought someone in after season three to explain what the fricking smoke monsters were up to and why those darned numbers were so important). But not before telling us that any sequel was likely to shift even further away from the Alien movies to which Prometheus had at one point been intended as a prequel-of-sorts.

Scott himself followed up in 2014 with a promise that the new movie would not feature any of the classic, HR Giger-spawned xenomorphs, the acid-blooded, multiple-mawed monstrosities that have haunted the waking nightmares of Alien fans ever since the director’s own pioneering 1979 slasher flick in space. “The beast is done. Cooked,” said Scott, speaking to Yahoo Movies. “I got lucky meeting Giger all those years ago. It’s very hard to repeat that. I just happen to be the one who forced it through because [the studio] said it’s obscene. They didn’t want to do it and I said, ‘I want to do it, it’s fantastic.’

“But after four [Alien films], I think it wears out a little bit. There’s only so much snarling you can do. I think you’ve got to come back with something more interesting. And I think we’ve found the next step. I thought the Engineers were quite a good start.”

But then, somewhere along the line, something seemed to change. Perhaps influenced by the palpable sense of disappointment over the idea of a Prometheus sequel with no connection to Alien, and presumably a whole lot more Lindelof-influenced portentous hogwash about the origins of mankind (which will still probably be in the movie), Scott announced that everything he had previously told us was wrong.

“There was always this discussion: is Alien, the character, the beast, played out or not? We’ll have them all: egg, face-hugger, chest-burster, then the big boy,” Scott told The Wrap in December. “I think maybe we can go another round or two.”

Far be it for me to complain about a film-maker giving the public what they want, but the entire process smacks of the kind of reactive film-making that caused fan-inspired movies such as Samuel L Jackson’s Snakes on a Plane to be such a mess. This is Ridley Scott, director of Alien and Blade Runner. Apparently changing his movie every five minutes because someone on the internet complained.

The latest shift to Alien: Covenant, previously titled Alien: Paradise Lost, previously titled Prometheus 2, etc etc, is that we will, after all, see the return of Noomi Rapace’s Elisabeth Shaw, Scott having earlier said the Swedish actor would not be involved. Those who watched Prometheus will remember that the film climaxed with Shaw and David the android heading off in one of the Engineers’ ships in search of the mysterious human-like extra terrestrials’ home planet. So it always seemed a little strange that part two would not continue the story.

Moreover, Alien fans have been here before, specifically when 20th Century Fox moved to kill off Newt, the little girl star of James Cameron’s Aliens, at the beginning of David Fincher’s disappointing Alien 3. Perhaps Scott didn’t want a similar fan revolt, so it now appears we will at least get to see what happened to Shaw, albeit most likely via some kind of flashback.

Alien: Covenant may yet turn out to be the best instalment since Cameron laid down the baton in 1986. And it may simply be that Scott is the victim of a modern internet culture that rebroadcasts every snippet of information about upcoming movies to the entire world. The gleaming carapace of the creature is cut away to expose the ghastly guts of film-making reality, leaving us all wishing we’d covered our eyes.

But the abiding sense here is that the new movie is suffering from the same lack of a clear flightpath that saw Fincher virtually disown Alien 3 and helped make Jean-Pierre Jeunet’s Alien: Resurrection a perennial source of the entirely wrong sort of horror. Once again it is film-making by numbers, as if the venerable space saga is being produced by a studio offshoot of Weyland-Yutani, the evil corporation that’s usually at the heart of everything rotten in the Alien universe. And as long-term acolytes will know all too well, it never ends positively when the men in suits have ultimate control of the mission.