“The Maze Runner” kicked off a fresh young adult film franchise this weekend when it raced to an $81.5 million debut globally.

Despite the monster grosses of “The Hunger Games” and “Twilight,” hit young adult films like “The Maze Runner” are the exception and not the rule.

Just ask the good folks behind “Ender’s Game,” “Beautiful Creatures,” “Eragon,” “The Giver” and “The Spiderwick Chronicles,” all of which seem unlikely to spawn future sequels. Others, such as “The Mortal Instruments,” probably won’t be generating new chapters, despite protestations to the contrary. Those stories may have devoted readers, but not enough people bought tickets when they made the transition from page to screen.

“Even with a baked-in must-see factor, you never know with this audience,” said Paul Dergarabedian, senior media analyst at Rentrak. “They change their minds when wind blows.”

Like “The Maze Runner,” these pictures arrived with literary pedigree allowing their backers to proclaim, “Based on the best-selling phenomenon,” while crowing about “brand pre-awareness.” That’s lovely. It’s just not enough.

“You still have to make a good movie that resonates with a core fanbase, but can stand on its own,” said Jeff Bock, a box office analyst with Exhibitor Relations.

Instead, these films seemed overly derivative. There was a dusting of female empowerment, a la “The Hunger Games,” or a hunky vampire or immortal in the vein of “Twilight,” and an endless array of post-apocalyptic backdrops as in, well, practically everything. Yet audiences rejected pictures that felt like Frankenstein’s monsters patched together by a committee in order to mirror the elements that studio executives had come to believe explained those films’ successes.

What set “The Maze Runner” apart was a cast led by “Teen Wolf” star Dylan O’Brien and a plot that had a group of teenagers struggling to survive a deadly labyrinth.

“It’s the first YA franchise that has a male protagonist,” said Chris Aronson, domestic distribution chief for 20th Century Fox, the studio behind the movie.

That meant that “The Maze Runner” was able to attract roughly an equal number of men and women, with 49% of the opening crowd being male. Appealing to men certainly helped “The Hunger Games,” which drew an opening crowd that was 39% male in 2012, and it worked this time around as well. In order to broaden the film’s appeal, “The Maze Runner” was marketed as an action-heavy thriller. That also helped it stand out from “The Giver,” “Divergent” and all the other dystopian adventures popping up on screens these days.

“These films are marketed by professional adults, not teenagers, so it can be hard to put your finger on what it is that that young audiences think is cool,” said Dergarabedian. “Six or seven times out of ten, you’re not going to hit that mark, but when you do, you’ve really got something.”

Having caught lightning in a bottle, Fox wasted no time announcing a sequel. “Maze Runner: Scorch Trials” will open on Sept. 18, 2015.

Not everyone agrees that young adult films are a knotty genre to untangle. After all, it can be hard to make any type of film pop in the era of Twitter, YouTube, videogames and other amusements.

“I don’t know what the batting average is for other genres, but young adult films are a relatively new thing and they may just be having more attention paid to them,” said Ben Carlson, co-creator of the social media tracking service Fizziology. “If you compare it to science fiction or R-rated comedies, it’s probably a similar batting average.”

What is different, Carlson argues, is the kind of success “The Maze Runner” managed to achieve. Filmed for $34 million, the picture is an economical bet that paid off, but it did not match the success of “Divergent,” “The Hunger Games” or “Twilight,” all of which debuted to north of $50 million.

“This film was a really solid hit, but it wasn’t a monster one,” said Carlson. “As a genre matures, you’re going to have more solid hits like this that aren’t $50 million opening blockbusters or ‘Why did that only open to $15 million?’ failures. We haven’t really seen that in the YA space until now.”

With that, a genre geared at kids comes of age.