The latest installment of Ridley Scott’s space-horror franchise, Alien: Covenant, hits theaters today. The series is coming up on its 40th anniversary, and over the course of its lifetime, it’s taken some interesting turns — and some downright unfortunate ones.

The franchise is already in a strange place, with the latest films sitting somewhere between prequels and sequels. And as with any long-running franchise, numerous entries can led to a complicated timeline. With the latest film coming out, it’s a good time to look back at the scope of the series, where it started, and where it’s currently landed.

What are the franchise’s core installments?

The franchise’s first film, Ridley Scott’s moody horror movie Alien, hit theaters in 1979, to widespread acclaim. James Cameron followed it up almost a decade later with 1986’s Aliens, which brought back Alien’s surviving protagonist, Ripley (Sigourney Weaver), and took the series in a more action-packed direction.

The 1992 sequel Alien 3 was directed by David Fincher, who went on to direct Seven, The Social Network, and Netflix’s House of Cards. Citing studio interference with the production, he essentially disowned it. In 2003, producer Charles de Lauzirika completely recut the film, inclining it toward Fincher’s original vision. The “Assembly Cut” was received much better than the original.

The next film to hit theaters was Alien: Resurrection in 1997. Directed by Jean-Pierre Jeunet (Amélie), it jumps centuries into the future and features a clone of Ripley, and people who want to use an alien queen from her body for military purposes.

There have been a fair number of Alien spinoffs over the years. Two Alien Vs. Predator movies crossbred this franchise with the similarly long-running science-fiction horror series that began with 1987’s Predator. A planned third AVP film would have led right into Alien, but it never materialized. There have also been extensive runs of comics and video games, both standalone Alien stories and Alien Vs. Predator stories. And more than a dozen novels have further expanded the Alien universe. But the dual core of the story has always been Alien and Aliens, the two feature films that helped define modern cinematic science-fiction horror.

So where’s the confusion?

The film series was pretty straightforward before Ridley Scott’s 2012 film Prometheus. That movie confused fans, because Scott conceived it as a film that came out of Alien’s “DNA,” but told its own standalone story. Still, it’s so close to Alien in the story details that fans couldn’t stop speculating about whether it was actually part of the Alien universe. Regardless, the film is set before the events of Alien. And Alien: Covenant works as a sequel to Prometheus, but also moves closer to setting up the original Alien.

The film series could have been more confusing: Fresh off Chappie, director Neill Blomkamp posted concept art for a fifth Alien film that was reportedly his next project. That film would have essentially ignored Alien 3 and Alien: Resurrection in an attempt to reboot the post-Aliens side of the franchise. However, with Ridley Scott’s Prometheus sequel in the works, Fox put the project on hold, and Ridley Scott basically said it’s not going to happen at all.

What’s the chronology of the films?

Chronologically, Prometheus begins in a couple of places. There’s an alien Engineer in the beginning of the film, seeding a new world, which might be Earth in the distant past, or might just suggest how the Engineers created humanity. In 2089, archaeologists Elizabeth Shaw and Charles Holloway dig up some evidence of humanity’s origins. And the actual Prometheus mission to find the Engineers takes place in 2093. Alien: Covenant takes place more than a decade after Prometheus, in 2104. A recent prologue links the events of the two films and fills in some of the gap, but not all of it.

From there, we get into the original films: Alien takes place two decades after Covenant in 2122, while Ripley wakes up from stasis 57 years later in Aliens. Alien 3 is set immediately after Aliens. Finally, Alien: Resurrection makes a huge jump to 2386.

What comes after Alien: Covenant?

There’s a two-decade gap between Alien: Covenant and Alien, and while this new film provides a direct line of action from Prometheus to Alien, it doesn’t entirely lead up to that original film. Scott has ambitious plans for the future of the Alien franchise: he says Alien: Covenant is “one of three sequels to Prometheus that will take the saga to the ‘back entrance’” of the original film.

He’s also said he can keep this story going for another six films. And he told IGN that he’s writing the next film now, and that he’s aiming to have it in production within the next 14 months. It’s unclear what that film will be about just yet. Back in March, Scott referred to a film called Alien: Awakening that might take place between Prometheus and Covenant, but he’s also referred to Blomkamp’s canceled film as Awakening.

Either way, it seems as though Scott is now looking to set up the original Alien with these new films, rather than mess with the post-Aliens era.

So where does the franchise stand now?

The Alien franchise seems to be split into two big arcs right now. Prometheus, for better or worse, helps set up the origins of Alien’s titular creature, while Alien: Covenant continues that arc. The other big arc is Ripley’s story, which began in Alien and continued through Alien: Resurrection. Given the drama surrounding the status of Neill Blomkamp’s canceled film, Scott and Fox seem a bit more keen on focusing on the franchise’s origins, rather than resurrecting Ripley for another outing.

This feels like a bit of an unfortunate choice, for two reasons: Blomkamp’s script was reportedly strong, but it also would have helped reboot the end of Ripley’s story. Alien 3 and Alien: Resurrection have both been widely condemned for the directions that they took the franchise: Joss Whedon, who wrote the original screenplay, said the filmmakers “did everything wrong that they could possibly do.”

The images of Blomkamp’s concept included Ripley and Hicks post-Aliens, an Engineer’s ship in a cargo bay, and of course, the xenomorphs themselves. It stands to reason that the film would have continued with some of the themes explored in Aliens, with the inimical Weyland-Yutani Corporation continuing to explore the potential of using the aliens as weapons. Most importantly, Sigourney Weaver said the film would give her character a satisfying ending. It was also meant to let Fox correct mistakes made in the previous sequels.

That attention is being spent right now on the origins of Alien, rather than going back to polish Ripley’s story. This could be down to simple practical reasons: it would be a marketing nightmare to introduce a new film on the heels of Alien: Covenant that’s really a sequel to Aliens. While standalone, out-of-continuity films are starting to be part of franchises, thanks to the success of Star Wars: Rogue One, it’s still a pretty newfangled concept from a franchise that’s much bigger than Alien. Presumably, in this sequel-driven industry, we’ll eventually see some sort of reboot or reimagining that either finishes out Ripley’s story, or takes the franchise in a different direction post-Aliens.