With a running-time of a full three hours, the new “Avengers” movie might more properly be subtitled “Endlessgame.” Like Wotan in “Die Walküre,” it appears that the godlike Marvel superheroes are prone to very long farewells. Their millions of fans probably won’t mind, of course, sad as they are to see much of the original crew signing off from the Marvel Universe—at least for now, in the form of not just the actors like Robert Downey, Jr. (Tony Stark/Iron Man), and Chris Evans (Steve Rogers/Captain America), who originated the roles in the series that’s now stretched to over twenty blockbusters, but probably in terms of Stan Lee’s cameos as well (though there might be one or two more already in the can).

But nostalgia can take one only so far, and “Avengers: Endgame” proves—like the “Star Wars” prequel trilogy—both predictable and grossly overstuffed with snarky lines and bathetic moments, though as sumptuously made as anything to have rolled off the Marvel assembly line. Having somebody like a film reviewer make such an observation shouldn’t bother the Disney company, Marvel’s new owner; this movie is probably as critic-proof as anything since “Gone With the Wind,” and since it gives series fans a heaping helping of what they obviously savor, they’ll eat it up.

In writing about the movie, one wants to avoid too many spoilers, but it’s a direct sequel to “Infinity War,” which ended in the vaporizing of half of humanity (and other species)—including plenty of the Marvel superheroes—by the villain Thanos (James Brolin) in an effort to cleanse the universe by ending overpopulation. It was clear that such a calamity could not be allowed to stand, and no sentient being could have thought that “Endgame” would do anything other than reverse it. The question was merely how clever a means of resurrection could the Marvel masters come up with?

The answer is: not very. Warning: Anyone who wants to go into the movie knowing nothing whatever about its general structure, or some of the details, is advised to stop reading here and just go see it. With that as a caveat:

After encapsulating the loss than mankind in general and the Avengers in particular have suffered through the experience of Hawkeye (Jeremy Renner), the film goes on to depict the gloom and doom that continues to envelop the earth for half a decade, despite the fact that Captain Marvel (Brie Larson) had shown up late to the party but still in time to rescue an important survivor, who goes on to make a new life for himself with a wife and child. But resilience has been in short supply—the half of humankind still alive seem benumbed after what seems like a secular version of the Rapture, and the surviving Avengers are estranged from one another and also in deep depression, even after they’ve killed Thanos, because he’s destroyed the Infinity Stones that could have been used to rectify the disaster he caused.

A gradual change of attitude among them is occasioned by the sudden return of Ant Man (Paul Rudd), who’d been trapped in the quantum realm and experienced the five years as of far shorter duration, and now suggests that time can be manipulated to allow them to go into the past, retrieve the still-existing stones and use them to change things back to the way they once were. The notion of time travel is pretty much dismissed as impossible by the two brains in the group—the Hulk (Mark Ruffalo), who’s embraced his greenness, and Stark—until the answer to the riddle abruptly reveals itself through some holographic modeling. So the script opts for the hoariest of devices, a time machine, as the solution to the need for multiple resurrections.

That effectively closes the initial third of the movie, and leads to what amounts to the second act—trips to the past by various Avenger teams, with a much-changed Thor (Chris Hemsworth) and Hulk, along with Hawkeye, rejoining the existing group of Iron Man, Captain America, Black Widow (Scarlett Johansson), War Machine (Don Cheadle), Thanos’ reformed daughter Nebula (Karen Gillan) and space raccoon Rocket (voiced by Bradley Cooper) to carry out a series of simultaneous missions to procure the rocks. Of course, each mission has multiple action scenes, cliffhangers, reversals, and encounters with figures from the time travelers’ past lives (along with close shaves and even deaths). It’s all exciting but in a fairly familiar way, since many sequences revisit sequences from previous installments seen from a different perspective and augmented with new sidelines that in fact are now their major elements.

Unfortunately by going into the past as they do, the time-travelers make the then-quite-alive Thanos aware of what they’re doing, setting the stage for the third hour of the movie, which is effectively a do-over of the big battle for earth from “Infinity War,” in which the surviving Avengers are joined by Captain Marvel, who seems curiously AWOL for most of it, until she intervenes at the very moment Thanos seems on the verge of wiping out our heroes to save the day—at least momentarily. That’s a cliché repeated over and over again as the CGI battle rages on for what seems like forever—until, of course, it’s over. Before that happens, though, virtually even Marvel hero and heroine in the Universe is given at least a few seconds of screen time, though you’d have to be a fanatic to identify each and every one as they flit momentarily by.

The final twenty minutes or so are devoted to wrapping things up post-battle. It’s here that the level of mawkishness reaches proportions as epic as the movie as a whole, with multiple scenes of families reunited (among the Avengers, that is: the rest of humankind is pretty much left offstage), fallen comrades mourned, people moving on and torches being passed to the next generation. So “Endgame” becomes both the final payoff for those who have stuck through all the mega-franchise’s episodes and a look toward what will certainly be a swarm of additional installments featuring newer or rebooted characters. It’s thus a canny device for the Mighty Marvel Machine to segue from one era into another.

For now, it’s enough to say that the large cast handles their duties with their customary efficiency, with Downey, Evans, Hemsworth, Johansson, Renner, Gillan and Ruffalo carrying the heaviest loads. Brolin, once again, has the unenviable task of appearing under pounds of makeup that make it impossible for him to give much more than a vocal performance. Everybody else in the large cast do what their fleeting appearances require. The picture ends with a sort of curtain call for all the survivors as the camera pans lovingly past them as they congregate for a special service

The technical work, too, is up to high Marvel standards, though the combat sequences suffer from the same visual murkiness as those in its predecessor. (Trent Opaloch was cinematographer, and Dan DeLeeuw supervised the army of effects workers.) Editors Jeffrey Ford and Matthew Schmidt apparently saw no need to speed anything up, especially not the sentimental stuff, which is dragged out with as much tenacity as dearth scenes in Puccini, and Alan Silvestri’s score weeps where necessary and thunders more often.

So are fans likely to be satisfied? You betcha: it will give them their fill of what they crave, a big, bombastic final chapter providing a fitting conclusion to a series that, over the course of a decade, redefined the expectations for superhero movies and turned them into the screen equivalent of comics on a monthly publication schedule. (“You’ll laugh! You’ll cry! You’ll cheer!”) Viewers unfamiliar with the series, if there are still any out there, will be less enthusiastic. (“You’ll be confused! You’ll fall asleep! You’ll wonder what all the fuss is about!”)

Here’s one spoiler that both groups might appreciate. Don’t bother waiting around until the endless credits roll out.