I wouldn’t say it’s a copy cat, but very close. One being underground in london through a series of train tunnels & features a male lead. ( Tunnels). The other is more about a teen girl & a gang of her ‘geek’ friends searching underneath the town of Manhattan. Other than the idea that they both take place underground & are focused on kids, I’d say they are definitely made for separate demographics. Each country gets their own underground story, like a Da Vinci’s Code for kids I suppose.