If you’ve ever dabbled with a Rubik’s Cube, you know it isn’t the easiest puzzle to crack. But despite the challenging nature of the game, it’s endured longer than most other toys of its generation—think Tamagotchis and Game Boys.

The Cube has seen enormous growth and success in its relatively long lifespan in the world of games, selling roughly 500 million units as it celebrates its 50th anniversary this year since architecture professor Erno Rubik discovered it—something he says has defied his expectations.

“It is a curious fact—one that surprises me as much as anyone—that for so many decades, during a time of an unprecedented technology revolution, fascination with such a simple, ‘low-tech’ object has survived. And, in fact, this fascination has evolved,” Rubik wrote in his book Cubed, published in 2020.

How Rubik’s Cube cracked the code for success

The Hungarian professor founded the colorful Cube—whose basic configuration involves a three-dimensional 3×3 grid that’s twisted and turned so each of its surfaces has the same color—in 1974, when he was just 29.

Rubik, now 79 years old, always had a proclivity for puzzles, and his academic background in art and sculpting became helpful instruments in creating the first prototype of the Cube we know today.

“I got an interest from [a] young age about problem-solving, challenges, chess problems and so on,” Rubik told Fortune in an interview.

Although he had created something that intrigued him, he couldn’t solve it for a month.

But once he did, it marked the beginning of the Cube’s journey—first, to shops in Hungary and soon after, the rest of the world.

“At first, it was important to prove to myself that it’s possible to solve. So, I thought well, if I can do it, somebody else can,” Rubik said, referring to the Cube philosophically as a reflection of life itself.

“The question is, how do you find your way between so many possible positions and how can you find your way back?”

The complexity and paradoxical nature of the Cube makes it more than just a game (that was solved by a 21-year-old in a record time of 3.13 seconds last year).

The Cube’s earliest boost in sales came in the 1980s, when Rubik took his creation to a fair in New York—in the three years that followed, roughly 100 million Cubes were sold, creating a frenzy that Rubik had never expected or seen before.

Rubik describes the Cube as a tool that’s helped him understand people.

Other academics also regarded it as such, including cognitive scientist Douglas Hofstadter, who wrote of the Cube in 1981 that “it is an ingenious mechanical invention, a pastime, a learning tool, a source of metaphors, an inspiration.”

With 43 quintillion solutions for the Cube, it can initially feel like an impossible task to tackle. But the Cube’s ability to confound people is also what’s drawn enthusiasts over the years, creating an entire universe of its own.

People have now solved the Cube blindfolded, competed in international championships for it, used it to demonstrate AI breakthroughs and much more.

It’s also earned a spot in pop culture, from featuring in a Spice Girls music video to appearing in Will Smith’s The Pursuit of Happyness.

All that has helped keep the Rubik’s Cube fresh in people’s minds.

How Rubik’s Cube is staying relevant in a digital world

The Rubik’s Cube, in tune with its shape-shifting ability, has managed through the decades to adapt and create a niche for itself despite other tech-driven forms of entertainment.

It’s this everlasting quality of the Rubik’s Cube that made its acquisition in 2021 a “no brainer” for Spin Master, the company’s senior director of games Sam Susz told Fortune.

However, the company also realizes the importance of catering to the digitally-savvy younger audience.

“It’s a challenge for the brand because it’s been around for 50 years. There’s been so many ways it’s been tried to be reinvented,” Susz said. “They [Spin Master] were trying to find ways to keep the iconic form and shape, but introduce new ways of play and new ways to interact with the Cube.”

Spin Master launched the Rubik’s Phantom Cube, which reacts to the user’s touch to temporarily reveal the color of a tile, adding a new challenge to the Cube by testing the player’s memory.

This variation, Susz said, appeals to cubers who want to up their skills, and to gift-givers who recognize the brainteaser in its original form with the added novelty.

The popularity of the Cube is reflected in its strong sales—in 2022, 5.75 million units of the official Rubik’s Cube were sold globally and that figure was up 14% year-to-date, according to figures from data firm Circana shared with Fortune by Spin Master in December.

The iconic Cube also occupied the lion’s share of the brain-teaser games market, with a total of 42%.

The realm of digital cubing is also growing, Susz pointed out, with new advancements in Bluetooth-enabled cubing allowing players to compete against one another from different parts of the world.

The Cube also has its own app for those wanting to solve it on their personal devices.

Spin Master has leveraged collaborations to keep the brand relevant and in demand—for instance, it recently launched a special line of Rubik’s Cubes in honor of Disney’s 100th anniversary.

The company has new launches through 2024 to make the 50th-year milestone for the Rubik’s brand, including partnerships with Marvel and Hello Kitty.

“We’re doing all sorts of unique collaborations that we think will appeal to kids and adult collectors,” Susz said.

As a brand that just hit its golden jubilee, it still feels young, vibrant and alive as it transforms to new times, while staying true to its roots. That’s perhaps why its founder doesn’t like talking about the Cube in the past tense.

“I think we can speak about the Cube not in the past. The Cube is in the present,” Rubik said.