In retrospect, it was obvious that Pokémon Go was going to change the franchise fundamentally.
It went far beyond what was expected of it - which was to be an entertaining, possibly shallow, kid-friendly collect 'em up. One former Pokémon PR told us that ahead of Go's launch they tried to send preview versions to press but only one journalist expressed any genuine interest.
Expectations weren't sky high.
It was of course more than just a cheap smartphone tie-in or some nostalgia fest for 1990s gamers. Sure, the 150 monsters brought in the adults, but the combination of the modern platform, technology and idea pulled in everyone else.
Yet it was still quintessentially Pokémon. Over the last 22 years, the 'mainline' series has layered on new concepts and strategic depth, yet at its heart it's a game about collecting, training, battling and hanging out with friends - and not online but in real life.
In that sense, despite its positioning as a spin-off, Pokémon Go was as true to the essence of the series as the more recent 'main' Pokémon titles.
"When it came to Pokémon's mainline debut on Switch - the first Pokémon created in a post-Go world - it was inevitable that the smartphone title would be involved"
Go also achieved something few other Pokémon spin-offs have managed before - it surpassed the popularity of the titles on which it was based. The cartoon series did a similar thing in the late 1990s, and the result was that it became part of the games themselves - with new characters and monsters appearing on TV before their video game debut. There was even a mainline title based on the anime in the form of 1998's Pokémon Yellow.
So when it came to Pokémon's mainline debut on Nintendo Switch (which is the first main Pokémon adventure created in a post-Go world) it was inevitable that the smartphone title would be involved.
Let's Go Eevee and Let's Go Pikachu is the marriage of a traditional Pokémon title and Go. The visuals, the catching mechanics, the co-operative gameplay, the fact you can see the creatures moving around the world... for a series that has changed only iteratively over its 22-year history, this is already shaping up to be the bravest departure for a mainline Pokémon game yet.
It appears to have been simplified, too. For a series that does have 22 years of iteration and history, the games have become increasingly aimed at core fans. Understandably so. Let's Go Eevee and Let's Go Pikachu appear to have jettisoned a lot of it - just like Go was able to do - and focus down on familiar monsters and a familiar world (this game returns to the same place as the very first Pokémon titles).
It makes sense for a franchise that wants to convert Go fans into players of the main RPG series. And despite what some fans might argue, this is a main Pokémon game. Junichi Masuda, the director at developer Game Freak and one of the original Pokémon creators, is leading its development. The word 'mainline' was repeated several times during last night's (unusually dark and serious) press conference. And the game is a big cross-company production, with Nintendo working on the Pokéball Plus accessory and Niantic enabling integration with Pokémon Go.
"Pokémon has a challenge that most video game franchises would die for - it has too many different fans"
It's a full Pokémon RPG designed to target this new generation that have come in via the smartphone, and that inevitably is going to upset some of the IP's core enthusiasts.
Pokémon has a challenge that most video game franchises would die for - it has too many fans. In particular, too many different fans that want different things. There are those that own every game, compete in the tournaments, collect the cards and watch each new cartoon series. There are those that loved the series in the 1990s and early 2000s, who dip back in now and again but couldn't tell your Chespins from your Pikipeks. And then there are the millions who discovered Pikachu and pals with 2016's Pokémon Go.
And everyone in between, too. In fact, last night's other game reveal - Pokémon Quest - is a smartphone and Switch game targeted at the most casual of Pokémon players.
Let's Go Eevee and Let's Go Pikachu is trying to satisfy as many of the fans as possible. Towards the end of the conference, Game Freak stressed that they believe these games will be a great "entry point" to the main RPG line, but that they're also unique enough to appeal to those that have been with them all along.
That might be the case, but it's still not exactly what some of its more loyal followers were hoping to see. They wanted Generation 8. They wanted new Pokémon, new worlds, new moves, new characters... the next chapter in a franchise they've stuck with since 1996.
That's why The Pokémon Company ended its conference by stating that it is working on a more 'traditional' Pokémon, too. There was nothing to show of this title, but the firm clearly felt it was important to mention - if only to counter any potential disappointment from those who wanted something a bit more familiar.
Yet the focus for now is on these Let's Go products. And their arrival this November comes at an opportune time for Nintendo.
Switch is still a hot product, but after its stellar first year - one dominated by hit title after hit title - things have quietened down. So far, 2018 for Nintendo has been full of niche titles, Wii U ports and Labo - which has yet to become anything especially significant. The end of the year will be different. Switch will hurtle into its second Christmas with Super Smash Bros and a new, ambitious Pokémon game on the release slate.
It's no wonder Nintendo expects to sell 20 million machines over the next 12 months.