Watching “Alien: Romulus” offered me the rare experience of seeing a solidly entertaining, well-executed movie that nonetheless left me feeling less optimistic about the future of the film franchise that it was tied to.

The original “Alien” film premiered in 1979, and it officially became a franchise with the release of its first sequel, “Aliens,” in 1986.

Both movies are roundly regarded as critical and commercial successes, but the track record of the roughly half-dozen feature films that followed has been much more uneven, to put it mildly.

The good news is that “Alien: Romulus” is easily the best film in the franchise since the first two.

What’s concerning is that almost all of its greatest strengths draw from recreating many of the best aspects of 1979’s “Alien” and 1986’s “Aliens.”

A number of intellectual properties have essentially become devoted to doing endless covers of their own greatest hits, so there are worse fates that could befall a film franchise.

But especially after the reductive pandering to fans of the “Alien vs. Predator” films of 2004 and 2007, followed by the initially promising but ultimately misfiring “Prometheus” prequels of 2012 and 2017, I can’t help but feel a bit dismayed that the best “Alien” film in decades is limited to the same three chords as the first two films in the series.

But enough inside-baseball analysis for the moment. If you have a stomach for suspense, bloodshed and weapons fire, “Alien: Romulus” is an effectively engineered delivery system for earned jump-scares, uncomfortable body horror, suitably impressive outer-space spectacle, none-too-subtle sociopolitical commentary and a few surprising touches of fond nostalgia.

“Alien: Romulus” is set during the in-universe time gap separating the events of the first “Alien” from those of “Aliens.”

In the midst of the 22nd century, everyone’s least favorite corrupt corporation, Weyland-Yutani, has made a dark, remote planet barely habitable for human life, to set up an isolated mining colony that manages to exploit its employees even worse than the real-life “company towns” of the late 19th and early 20th centuries.

The inhospitable environmental and labor conditions make one group of orphaned young workers desperate to escape their forcibly extended contracts, enough to risk salvaging a derelict space station that’s drifted into the vicinity of their planet.

Their goal is to retrieve the suspended animation chambers that should enable their crew to survive the nine-year trip to the nearest neighboring planet.

Unfortunately for them, what they don’t know  until they’re on board the space station, is that it went dead because it made the mistake of salvaging some alien survivors from the deep-space wreckage of another derelict craft.

While Sigourney Weaver was a reassuring constant in the first four “Alien” films, she hasn’t come back to the franchise since 1997’s “Alien Resurrection,” but “Alien: Romulus” does feature the return of one familiar face, which I won’t spoil but never expected to see again.

To this film’s credit, that character’s appearance is entirely in keeping with the “Alien” franchise’s established mythos, and perhaps more importantly, received the blessing of the actor’s estate.

The new faces in the cast acquit themselves well, albeit a bit unmemorably overall, with Cailee Spaeny continuing her standout streak from last year’s “Priscilla” and this year’s “Civil War,” while David Jonsson caught my attention for the first time here, turning a role that initially threatened to bring out a problematic portrayal into something uniquely nuanced and unnerving.

I grew up on enough of Isaac Asimov’s classic “three laws” robot stories that I appreciated seeing yet another way in which a robot’s programming could be perverted, by acting on behalf of what’s ostensibly best for the maximum number of human beings.

Easily the most novel features of this “Alien” film are its innovative zero-gravity combat sequences, and its admittedly scientifically inaccurate race against time, for our protagonists’ spacecraft to avoid colliding with the Saturn-like rings of the planet.

By definition, “Alien: Romulus” is not necessary viewing for fans of this franchise, since its status as a “mid-quel” ensures that it cannot have any ripple effects on the broader mythos, but at the very least, it makes the act of treading water compelling to watch.