Image copyright Getty Images

It's taken 23 years, but this weekend Pokémon come to cinema screens in their first ever live action movie.

Detective Pikachu stars Ryan Reynolds as the titular mouse-like creature as he tries to solve a mystery with the help of some human co-stars.

And according to Radio 1's Ali Plumb, the film is good - although it doesn't make a huge amount of sense.

But for fans of the franchise - which is all about keeping animals inside balls and making them fight each other - that's more than enough.

"I need to be involved in the conversation somehow because it's one of my favourite things ever. Even if it's terrible, I need to see it," 28-year-old web developer Mark Victor tells Newsbeat.

He says his playground at school was always buzzing with Pokémon gossip about rumours of tricks to play in the games to find rare Pokémon like Mew - rumours that always turned out to be false.

Image copyright Mark Victor Image caption Mark says that Pokemon, to him, is "a nostalgia thing. It's like a big warm hug"

"As a child, I'd wish that if science could do just one thing, I'd really like them to make Pokémon real so I could finally become a Pokémon trainer," he says.

"The fantasy of these creatures in the wild that you can become friends with, train and really become amazing at something that seems so accessible was definitely something I wanted to do - even if it was a bit silly."

How Pokémon connected with autistic people

It was a similar story for 20-year-old Ellen Jones, a student and campaigner who lives in London.

"It very much created a world I wanted to live in," she tells Newsbeat.

"Pokémon is about humans living and working together, fighting bad guys and I think I definitely idolised that."

But Ellen also connected with the world of Pokémon because she, like creator Satoshi Tajiri, is autistic.

Satoshi created the games to share his love of collecting insects with other people, and that's what Ellen fell in love with.

"Collecting things and strategy are very much things that autistic people love so it makes perfect sense in hindsight that I became obsessed with it," she says.

"I really liked the strategy elements of it, the ability to memorise the different statistics and data, and the fact there were different types of Pokémon in different regions."

Image copyright Criag Simmonds Image caption Ellen says she hopes Detective Pikachu lives up to the Pokemon world she imagined

Ellen first started playing Pokémon Diamond on the Nintendo DS when she was 10 years old, and when she moved to London to study, she used the recent Pokémon Go mobile game to make friends.

"One of the first things I did when I moved to London was, the day after I moved into halls, I went to a Pokémon meet-up," she says.

"Everyone was sat playing Pokémon. It was a way of going somewhere in a city where I didn't really know anyone and making friends over this shared interest and bonding over this game."

From failure to phenomenon

Satoshi Tajiri came up with the unlikely idea for Pokémon when he realised children in the cities didn't have the same opportunity to enjoy nature as those living in the countryside.

He began to develop the concept for a Game Boy game, involving collecting, trading, and evolving the powers of battling monsters - guided by their human trainers.

Image copyright Getty Images Image caption Ash Ketchum and his electric mouse Pikachu are the stars of the long running Pokemon cartoon

But his first pitch to Nintendo failed and Satoshi had to go back to the drawing board.

After a revised plan, Satoshi succeeded, but it took a whole six years of development with Nintendo before the first versions of the game, Pokémon Red and Green, were released in Japan in February, 1996. A third version, Blue, which included bug fixes for the previous two, soon followed.

A brief Pokéhistory

Pokémon's original titles - red, blue and green - are estimated to have sold more than 31 million copies worldwide.

Successful sequels, updates and spin-offs were released to huge success on various consoles in the years that followed, but it wasn't until Pokémon Go in 2016 that the whole world fell in love with the game for a second time.

Pokémon Go was downloaded more than 100 million times around the world in under a month when it was released.

Image copyright Getty Images Image caption The first Pokemon movie, imaginatively entitled Pokemon: The First Movie, was released in 1999

There have also been 23 animated movies and six TV series that have been on screens since 1997 - the same year the trading card game was released in Japan.

Pokémon didn't hit the west though until 1998 when the cartoon came to American TV screens, and later the same year the video games were released. The card game wasn't released until shortly before 2000.

Image copyright Getty Images Image caption Kathryn Newton, Ryan Reynolds and Justice Smith star in Detective Pikachu

5 Pokéfacts you might not know

1. Pikachu's name is mix of the Japanese for sparkle, pikapika, and the sound of squeaking, which is chūchū.

2. The name of Pokémon only came about because of a copyright issue during the creation of the video game - its original name was Capsule Monsters, before it changed to CapuMon, then Pokémon.

3. Drowzee, the dream-eater Pokémon, is based on a tapir. In South American folklore, the mammal would use its long snout to eat dreams as people slept.

4. The first Pokémon to be created was actually the rhino-like Rhydon, not Pikachu.

5. The most sought-after Pokémon trading card to this day is Charizard, who is one of the Pokémon seen in the trailer for Detective Pikachu.

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