This week, Warner Bros released the first trailer for Pokémon: Detective Pikachu, a live-action Pokémon film due for release in May. At the time of writing, the trailer has been viewed 10m times on the official YouTube channel alone, and tens of millions more via Facebook and Twitter. Vice declared the trailer “extremely cursed”. It’s been a top trend on all night, with hundreds of tweets a minute. So what is it about this trailer that has provoked such an intense reaction?

Pokémon is a pretty sacred source of childhood nostalgia for most millennials – a lot of us think about it the same way that 45-year-old men think about Star Wars. Anything that taps into (or messes with) childhood memories has a tendency to reduce grown adults to filling comment boxes with emotionally charged reactions to the size of a fictional creature’s paws.

This is the first ever live-action Pokémon film. The Pokémon movies we saw as kids were all cheap-ish anime jobs (though that didn’t stop us from crying in the cinema when Ash died and his Pokémon pals revived him with their grief-stricken tears). Detective Pikachu is about a failed Pokémon trainer (Justice Smith) with a missing father, who meets a Pikachu in a deerstalker hat and finds that he can understand the creature, like Kanto’s own Doctor Dolittle.

This is another big source of weirdness: in this film, Pikachu talks. Not only that, but he talks in the voice of Ryan Reynolds. Pikachu has only ever said “pika-pika! Chuu!” before. Now he shares a voice with Deadpool.

Then there’s the fact that the Pokémon themselves are newly realistic, with natural-looking fur and skin. This is really creeping people out. Pikachu himself looks… hairy. Mr Mime – who, let’s be honest, was already nightmare fuel – has an uncanny plasticky face. Charizard is a terrifying, scaly dragon. Jigglypuff is a fuzzball with a curl of human-looking hair. The Verge proclaimed this as proof that Pokémon shouldn’t be realistic, but that begs the question: what is the alternative? Cartoon Pokémon in a real world, a la Space Jam?

The vibe of the trailer is a world away from the two-dimensional, colourful Pokémon worlds of the games and anime, and it’s giving people tonal whiplash. The poster goes for a modern noir feel, with city neon reflected in street puddles.

They might be weirded out by the trailer, but Pokémon fans aren’t disappointed with it – the responses have mostly been extremely positive, though it’s a shame the petition to get Danny DeVito to voice the hero never worked out.

The film is out on 11 May. Expect cinemas to be packed not with kids, but with people in their late 20s and early 30s trying to navigate their own uncanny valley.