Things weren’t looking so bright for Nintendo back in 2004.

The company’s latest console, GameCube, had failed to make any real headway against Sony’s mighty PlayStation 2. Worse, console race newcomer Microsoft’s Xbox had more or less worked its way into a dead heat with GameCube. Sega might have retired from first-party status, but Nintendo couldn’t breathe easy for a moment.

And fresh threats loomed in the handheld gaming market as well, which had belonged almost exclusively to Nintendo for a decade and a half. Venerable warriors like Atari and Sega had tried and failed to make a dent in Game Boy’s dominance with the Game Gear and Lynx, respectively, as had up-and-comers like SNK and Bandai with the Neo Geo Pocket and Wonderswan.

Even the most durable fortress eventually falls, however, and Nintendo’s small-screen fortunes seemed doomed to fail against Sony’s newly announced portable PlayStation. The PSP would launch in Japan before the end of the year, it boasted console-quality power, came wrapped in a sleek and decidedly grown-up physical design and most of all promised to run a stunning library of software. Nintendo’s Game Boy Advance seemed a child’s toy in comparison — a criticism that was hardly blunted by the fact that its most popular software involved kiddie mega-franchise Pokémon.

The continuing success of GBA and Pokémon had kept Nintendo afloat despite the GameCube-shaped anchor around the company’s neck. If that money-maker were to evaporate, what then? Did SEGA’s exit from the hardware console business portend Nintendo’s future as well?

Nintendo makes a bold move

Seemingly desperate, Nintendo made a surprise announcement: It would release a new handheld system by the end of 2004, slightly ahead of PlayStation Portable and well ahead of the expected generational cycle. The GBA was barely three years old at this point.

This new system, the DS, left observers downright befuddled: While it offered modest 3D capabilities, it also sported two screens, one of which had touch capabilities. It looked like no other console that had ever existed before, its benefits and potential were fuzzy at best, and it competed directly with Nintendo’s own GBA. It seemed absolutely doomed, and perhaps Nintendo with it.

Customers disagreed, however. The DS became the second best-selling console ever made, landing just shy of PlayStation 2. It saved Nintendo, at least in the form we recognize, in the company’s darkest hour.

It also doomed handheld gaming.

iPhone gaming built on the foundation of the DS

Handheld consoles would take more than a decade to fully fade away after the launch of the DS, but traditional portable systems hover at the edge of extinction in 2018.

Nintendo will keep supporting the 3DS, but hasn’t announced a successor outside of the Nintendo Switch. Sony bailed on PlayStation Vita and has offered no indication that a follow-up will ever exist. And, while Switch certainly offers optional portable play, it is not a handheld system in the truest sense of the word. It performs better docked, and the undocked unit isn’t exactly pocket-sized. The Switch, if anything, feels like an admission that modern portables need to differentiate themselves by being closer to consoles in order to compete.

Portable gaming is no longer the sole domain of Game Boy’s children, and it’s all DS’s fault.

Well, maybe not all. But certainly the innovations that catapulted DS to its improbable success helped define the gaming format that would replace traditional portable systems, and within the DS’s own lifetime, at that. Namely, mobile games.

The DS seemed an unlikely countermeasure to the threat represented by Sony’s PSP in terms of raw technology. Its two screens, combined, offered lower resolution than Sony’s device, and its 3D processing power (which was only fully available to one screen at a time) clocked in closer to the Nintendo 64 than the near PlayStation 2 level horsepower available to PSP. And where Sony’s hardware design spoke of high-end sophistication, the original DS arrived in a case that sported all the elegance of a lumpy grey brick.

What the DS did offer, however, was a sort of user-oriented versatility that made the system accessible to a far wider audience than the hardcore players the PSP targeted. Nintendo, to its credit, realized this fact from the outset and built a massive portion of its software library around that expanded audience.

Newly minted Nintendo of America president Reggie Fils-Aime referred to the company’s approach as the “blue ocean strategy,” which involves finding uncontested space in which no one else is competing. But what consumers saw were games that looked unlike anything those ever seen on competing consoles. Pet simulators that would let you scratch your puppy’s ears with a stylus! Quiz games designed to keep aging brains active! Detective mysteries that turned the portable console into a tiny, animated paperback novel!

Sure, there were RPGs and action games and all the usual fare, but the enthusiasm with which Nintendo pursued the casual gaming audience, and even people who had never gamed at all, helped the DS to stand apart.

The low cost of the DS hardware (combined with the low cost of developing software for its humble hardware) allowed Nintendo to position the system as an inexpensive competitor to the PSP, with a wider library of games and a diverse array of game concepts.

That tactic had served Nintendo well since the days of Game Boy and Tetris, but DS elevated this approach to an entirely new level. The DS drew in consumers that Sony had never considered courting. The derisive sneers of “non-games” with which core gamers dismissed the likes of Nintendogs didn’t stop those titles from selling tens of millions of copies to everyone else.

The DS awakened an interest in casual play that had never really existed before. Aside from occasional crossover PC hits like The Sims and Bejeweled, video gaming as an industry hadn’t made much effort to appeal to anyone but boys and young men since the medium’s earliest days. The DS made those “outsiders” a primary target, convincing non-core consumers not only to play but even to adopt a habit of carrying their own pocket-sized game console with them into the world.

So, when smartphone gaming matured a few years later, the general public was far more open to the idea of gaming than they would have been before the DS blew up. The timing couldn’t have been worse for Nintendo: It had basically primed the entire world for iPhone. The DS reached market saturation right around the time the first gaming apps launched on iPhone, and DS’s tech paled to the capabilities Apple and its imitators offered. Apple needed simply to step in and claim their prize.

Not only had DS opened the door for mobile gaming apps, it had served as a test bed for the difficult process of sorting out best portable casual design practices, too. A huge part of DS’s appeal had to do with its touch screen, which posed a far lower barrier of entry to interacting with games than the bloated controllers of core consoles. Analog triggers and clicky sticks have tremendous value for complex shooters and racing games, but they’re intimidating to players who haven’t grown up with them.

On the other hand, your grandfather doesn’t need a tutorial to understand that tapping a stylus on an object on a touch screen allows you to interact with it. Touch-based gaming worked so well, in fact, that Apple felt comfortable abandoning detached control functions altogether in favor of touch for the whole ecosystem. The future was in screens, not controllers or buttons.

Similarly, Nintendo had included wi-fi features in the DS, but the company was as reluctant then as now to embrace full-scale online play. Head-to-head online games appeared on the DS (a la Mario Kart), but you were just as likely to find Nintendo sticking to asynchronous networked features instead. Consider “Bark Mode” in Nintendogs, the passive, proximity-based sharing system that paved the way for StreetPass. Or Animal Crossing’s online mode, which largely focused on letting other people visit your town and fool around on their own time.

This asymmetric approach to social gaming would become a fixture of major mobile hits like Words With Friends. Those mobile games lack direct head-to-head play options in favor of providing periodic updates on your friends’ progress, allowing you to ping pals to beg for collaborative boosters, or modernizing the concept of playing by mail with turn-based networking.

Even the play patterns that define mobile games came into focus through Nintendo’s DS library. Casual fare such as Animal Crossing, Brain Age and Nintendogs all adopted mechanics that discouraged extended play sessions in favor of quick daily check-ins.

Nintendo primed the entire world for iPhone

There was little value in sitting down with Brain Age for a few hours. Rather, the idea was to play for a few minutes every day and chart your progress over time. Animal Crossing offered a wide array of in-depth play features, but its central play loop emphasized running errands and digging for fossils around town for around half an hour each day. DS games hadn’t invented this daily micro-session approach; everything from massively multiplayer games to simple Tamagotchi LCD toys had also explored the concept. The DS library simply demonstrated how perfectly it fits handheld gaming.

The industry paid attention. Today, the most profitable games on iOS and Android have incorporated the idea of short daily sessions as the core of their design. From Candy Crush Saga to Nintendo’s own Dragalia Lost, mobile games seem to fare best (at least for their creators’ bottom line) when they force players into short, regular sessions that include limitations which can be removed for a price.

The arrival of iPhone effectively caused the DS market to implode. When the time came to launch the DS’s successor, 3DS, Nintendo found itself facing a difficult uphill battle to push back against the mobile platforms and games that had patterned themselves after the DS.

While 3DS eventually did prove itself viable, it has only sold about a third as many systems as the DS managed, and only then after Nintendo swallowed a huge serving of humble pie by revising its 3DS strategy a few months into the system’s life by slashing the hardware’s price and offering a load of free games to early adopters as an uncharacteristic mea culpa. After all, mobile games offer all the things that made the DS so appealing, and they do so on devices that everyone carries around in their pocket.

Even Mario has a tough time competing with that kind of convenience — just look at the underwhelming performance of Super Mario Run as proof.