Sony had cannibalized a market that Nintendo once owned.

Both in games media and behind-the-scenes at development studios and publishers, there was an uneasiness at play.

Satoru Iwata, president of Nintendo from 2002 until his death in 2015, saw things similarly.

Nintendo DS

An pre-release version of the Nintendo DS from the Electronic Entertainment Expo (E3) on May 13, 2004David McNew/Getty Images

Games have come to a dead end, he prophetically toldMainichi Interactive in 2004.

PSP was a multimedia machine before [there was] a smartphone, Cartwright says.

I think the dual screen formats confused me, Park says.

That thing didnt sound attractive to me at all.

I think it was really bold to abandon that naming, it was a huge gamble.

It looked so ugly, MacDonald says.

Its very Y2K and plasticky.

It might be Nintendos least beautiful console and it didnt fit in your pocket very easily.

It had a more modern aesthetic and it was a fashion moment, according to Cartwright.

It was a lifestyle machine, continues Cartwright.

The diversity and variety of how you might play your games was a big part of the DS appeal.

The dual screen aspect has always really been a weird little obsession of Nintendos, MacDonald claims.

The two screens served a dedicated function in the DS software, in some more impressive ways than others.

It was the most mind blowing thing about the DS, states Cartwright.

It enabled a new realm of gameplay which landed so well with a casual audience.

It was key to their success, adds MacDonald.

Wi-Fi wasnt widespread in 2004 either, but the DS wireless connection abilities made an impact beyond gaming.

You turn the DS on, you have options, and youve gotPictochat, continues Cartwright.

Everybody gravitated towards it.

Its the digital equivalent of passing notes in school, says MacDonald.

Its the same impulse as MSN Messenger; these little tokens of connection between people.

Nintendo is quite good at these one shot fun ideas.

PlayStation and Xbox were taking off withCall of Duty, and heres Nintendo with a little note passing app.

But if the God of Games was working so much, could we give up?

Miyamoto had incredible stamina.

I dont know how far the core Nintendo base takes you, he says.

You really have to go out of your way to get a different demographic buying these games.

If they just rested on games likeMario 64 DS, I dont think it would have done great.

Its a great game to have in the mix, but its in its own bubble.

A huge success story for Nintendo during the DS generation wasDr.

I remember getting into a heated argument in the pub with someone about it being a game at all.

A wild swing at the time developed into a core tenant for Nintendo.

Taking game elements and putting them into more of a lifestyle concept, that was pioneered withBrain Training.

And they seeAnimal Crossingand know thats a game that has a low hurdle to entry.

You dont have to know much about games to pick upAnimal Crossingand play it.

Thats true from kids to grandparents.

Along with the removal of region-specific holidays like Christmas and Halloween,Wild Worldfully utilized the DS Wi-Fi capabilities.

Wild Worldalso succeeded at appealing to a female market which, at the time, was almost entirely untapped.

Women ended up comprising 44 percent of DS owners worldwide.

For Park,Animal Crossingis a microcosm of a bigger achievement of the DS bridging hardcore and casual markets.

Nintendo was catching on to how well habit forming games work on the mobile format.

Then theres cozy gaming and the rise of engagement gaming too.

This connection extends to handhelds in general.

Its a bridge between hardcore PC people and people who are wary of PC gaming.

The DS is a huge link between the Game Boy towards the future of gaming.

The Future of (Nintendo) Gaming

Reinvention was core to Satoru Iwatas philosophy as Nintendos president.

With 150 million units sold, the DS strategy stands as one of the most ingenious in gaming history.

As Nintendo gears up for their next generation, could that strategy work again?

Replicating it wouldnt work anymore.

Thats not needed now.

I think theres room for casual titles, but not as the focus, Cartwright adds.

Give it a couple of decades, we might see a much more diverse casual gaming world.