Pokémon is a fad. It has been for 20 years now.

Pokémon made its first real splash in the U.S. back in December 1997, when the media reported on strobing lights in a Japanese cartoon called “Pocket Monsters” that caused a wave of sickness and seizures among its young viewers. The story of the seizure-inducing cartoon caught lots of attention in America, most of it unflattering (those Japanese, so zany!!). “Pocket Monster seizures” had become a meme both online and off by the time the games arrived here a year later, under the catchy name Pokémon.

Despite the salacious initial buzz, Pokémon launched to immediate success in the U.S. thanks to Nintendo’s massive media blitz. The first American games, Pokémon Red and Blue, raked in $70 million in earnings in their first six months on the market. The games were still burning up the Game Boy sales charts when The Simpsons aired its 1999 episode “30 Minutes Over Tokyo,” in which the entire family was rendered catatonic by a popular Pokémon satire, “Battling Seizure Robots.” A few months later, South Park took its own swing at Pokémon with the episode “Chinpokomon,” in which the community’s parents fretted that their kids had become swept up by a Pokémon-inspired fad. Meanwhile, major publications like Time and Newsweek explored the Pokémon phenomenon in alarmist terms, ultimately assuring parents that it would all go away on its own.

The subtext of these episodes and articles echoed the conversations happening in the era’s gaming forums about Pokémon: distrust of an addictive, kid-friendly import, mitigated by confidence that children’s collective fascination would eventually subside. America had survived the collective mania over Transformers, the Nintendo Entertainment System, Teenage Mutant Ninja Turtles and Mighty Morphin’ Power Rangers. Surely we could survive this latest assault on our impressionable youth as well. Pokémon would fade in time.

Two decades later, the series’ sales figures have refused to bear that assumption out. Going by the “core” games alone — to say nothing of spinoffs — Pokémon’s sales have only grown through the years. The franchise debuted on the original Game Boy, where the four different international versions of the first generation of games (Red, Green, Blue and Yellow) sold more than 45 million units combined. The most recent generations of games have appeared on Nintendo 3DS, where combined sales of new and remade core titles have topped 55 million units. Strange, right? 55 million is more than 45 million. Those aren’t the sorts of figures you normally associate with a fading gimmick — and they fail to take into account the millions of people playing Pokémon Go for free on their smartphones in tandem with the 3DS titles.

Of course, Pokémon Go was a fad, too. Just ask any number of pundits! It was a short-lived phenomenon. Just a flash in the pan, really. Why, it’s faded to ... a mere 5 million current players? And it’s seen its the highest numbers since launch over the past few months? Wait, that can’t be right. Can it?

It’s hard to name another franchise in gaming that’s managed to produce such consistent results for two decades. The initial release in each of Pokémon’s seven generations of games ranks among of the 50 best-selling games of all time. That’s each one, individually, claiming separate slots of the top-50 list. Oh, and the anime? The that one that caused so many kids to visit the hospital? It’s still going, and it’s accompanied by a new movie each year. The Pokémon film franchise even returned to the big screen in the U.S. for its two most recent movies, after more than a decade as straight-to-video fare — hardly a sign of a franchise in decline.

Pokémon embodies everything good and appealing about video games

You’d think Pokémon might have earned a pass by now, but no. With each new announcement, forum pundits and armchair analysts still trip over themselves to point out the inevitable end in store for Nintendo’s most adorable juggernaut. We saw it with Pokémon Go, and we see it with the series’ next major release, Let’s Go, Pikachu! and Eevee!. Let’s Go certainly seems unlikely to fail, given that it drafts off two hot tickets at once by combining Pokémon Go with the Nintendo Switch. The franchise doesn’t appear to be in any danger of fading from glory for the foreseeable future. But what, precisely, accounts for Pokémon’s enduring appeal? How has a series so widely decried as a superficial pop-culture blip managed to stay with us for so many years?

Pokémon transcends age and skill to find success

In many ways, Pokémon embodies everything good and appealing about video games. It touches on the social and competitive elements that fuel the likes of Fortnite, while presenting a world all its own. Pokémon manages the rare trick of having immense kid appeal while nevertheless possessing the depth to sustain adult interest.

Indeed, the sustainability of Pokémon didn’t truly become clear until several years after the original games’ debut. With extensive toy lines, a cartoon and a card game to prop up Pokémon’s 1998 U.S. launch, Nintendo clearly aimed the series at kids at first. Five or six years later, though, something important happened. The late ’90s tweens who had been obsessed with finding a holo-foil Charizard card and screaming commands to Pikachu via their N64 microphone peripheral grew into teens who were entirely too cool for Pokémon.

Then they made it to college. As they entered that phase of their life, many began the time-honored tradition of taking stock of their childhoods — right as Nintendo and Game Freak launched Pokémon FireRed and LeafGreen, upgraded remakes for Game Boy Advance of the “generation one” titles. Suddenly, a generation of reformed Pokémon fanatics had a fresh and contemporary reason to discover that the underlying design of those “kids games” had enough substance to keep them playing as adults. Yes, Pokémon are your lovable friends, but the systems involved in making them fight for supremacy have staggering depth.

Pokémon came into being as an intimate, intricate labor of love

Pokémon also taps into the social aspect of gaming at every level. The earliest video games were very much about collaboration and competition. Primal computer works like Spacewar!, Zork and Rogue emerged from a communal tech culture that encouraged programmers to share ideas and innovations with one another; the earliest arcade games, on the other hand, existed as multiplayer contests for supremacy. Pokémon encompasses all of this. Its link battles allow players to pit their favorite teams against one another and test their preferred strategies. At the same time, Pokémon demands cooperation. Every generation ships in dual versions, each of which contains unique monsters that can only be acquired (and some of which can only be evolved to stronger forms) by way of trading.

And make no mistake: The concept of trading and collecting is baked into Pokémon at its primal level. The game’s motto, “Gotta catch ’em all,” turns one of the central conceptual pillars of video game design into an explicit marketing tagline. Like socialization, acquisition has always been woven into the fabric of gaming. Eating bonus fruit for more points; gathering 100 coins for a 1-up; earning fancy hats to wear into your next team deathmatch: Pokémon applies that element to a real-world analog — bug collecting — but adds a fantasy element in which those virtual combat beetles appear as cute, memorable creatures of all stripes. Players often “imprint” on different Pokémon the same way they would on a pet, and it’s become something of a truism among fans of the series that they’ll always prefer the monsters that defined whichever generation of games introduced them to the series. As a bonus, the creatures tend to be highly merchandisable; the idea then becomes not simply to collect ’em all in-game, but outside the game as well.

Like the games themselves, the Pokémon you collect work on multiple levels. Each creature possesses specific traits that define how they function in combat. Drawing from the elemental concepts of RPGs like Final Fantasy, each Pokémon is defined by its “type,” innate strengths and weaknesses that turn combat into an advanced form of rock-paper-scissors. Types also play a significant role in the nature of the ability each creature learns as it grows in experience, though players also have a certain amount of freedom to further customize these skills to meet their own requirements.

This, in turn, leads into the game’s third and final layer of gameplay appeal: high-end competitive play. With a roster of monsters approaching the 1,000 mark and nearly as many skills for them to learn across a dozen different elemental types, the engine powering Pokémon’s combat and character growth hides considerable complexity — including some secret factors that obsessive fans have figured out through extensive study. In addition to once again demonstrating the communal collaboration that Pokémon fosters, decrypting these hidden statistical values opened the door for the highest tier of serious competitive play, where spreadsheet warriors selectively breed their creatures across multiple generations in search of the perfect balance of statistics to complement their chosen play styles and preferred tactics.

Of course, you don’t have to play at that level to enjoy the game. That’s a big part of what gives Pokémon such broad appeal. Whether you’re a kid in primary school barely still learning to read the combat menus or a grown adult determined to perfect your favorite battle team, Pokémon works for you on all levels. To Game Freak’s credit, the studio has had the wisdom not to change the games too much over the years. This, too, feeds into play patterns, in which kids obsess over Pokémon, grow out of it and return to it with the perspective of an adult, and find something completely different to enjoy about the series. The games change very little from one generation to the next, so that when you feel the itch to go back to Pokémon after letting your interest lie fallow for a few years, it’s like returning to your hometown after spending time abroad. Things look a little different here and there, but on the whole, it’s all pretty much the way you remember it. It becomes comfortable, and comforting.

Perhaps most importantly, Pokémon comes by its appeal honestly. It wasn’t created by a vast corporation ticking off a checklist of consumer endorphins to stimulate. On the contrary, it was a tortured work by a handful of creators who labored for years to perfect it. They infamously ended up producing program code so quirky and patched-together that tech genius Satoru Iwata had to step in and revamp it in order to make the international localizations possible. In short, Pokémon came into being as an intimate, intricate labor of love; the sprawling multimedia corporate franchise sprang up around it only after it became a word-of-mouth hit in Japanese schoolyards.

The game’s lead designers, Satoshi Tajiri and Ken Sugimori, conceived of Pokémon as an attempt to translate their own enthusiasm for competitive bug collecting into a video game concept that would take advantage of the Game Boy’s link cable connection. They began working on the idea for Pocket Monsters — initially called “Capsule Monsters” — around the time of the Game Boy’s launch in 1989, if not before that. By sometime in 1990, the world map and structure for the game’s map, the Kanto region, had been finalized, along with designs for more than a dozen monsters. Yet Pokémon didn’t debut in Japan until 1996; Tajiri and Sugimori’s studio, Game Freak, spent all that time defining and refining the game to make sure it lived up to their dreams and expectations.

It’s like returning to your hometown after spending time abroad

The fact that Tajiri based Pokémon on beetle collecting accounts for one of its most important design considerations: effort. By no means is Pokémon the only video game about collecting and acquisition, but capturing Pokémon requires genuine effort. Unlike modern open-world games, where you have a checklist and a map that turns these tasks into a rote process, Pokémon forces you to go to considerable lengths to acquire new monsters.

At the most basic level, you need to fight a monster and whittle down its health before you can claim it as your own. But each monster only appears in certain areas, sometimes only at specific times of day. Some need to be traded for, or else acquired by completing a single-player quest, or mutated from other creatures under unspoken conditions. Filling out the index of Pokémon in each is no easy task, and it creates a connection that underscores the completist drive in way you don’t experience from opening a succession of random treasure chests in Assassin’s Creed or shooting a bunch of pigeons in Grand Theft Auto.

And Pokémon Go, fad that it is, makes the journey to capture Pokémon literal. It rewards players for venturing to new places, tying certain creatures to different regions — even other countries.

So yes, Pokémon is a fad. Gaming’s most enduring fad, still doomed to imminent obsolescence two decades after its faddish, superficial debut. A fad in which each new entry in the series reliably sells 10 or 20 million copies apiece. Just you wait. It’ll be a forgotten memory any day.

Yep. Any moment now ...