13 July 2016 Last updated at 14:42 BST
The game has not been officially released in the UK, but keen gamers have found ways around the app's country restrictions to get early access.
However, the chief executive of children's charity NSPCC has urged the app's makers to add safety measures before its UK release, warning that adults could use it to prey on children.
Pokemon Go has become a phenomenon in the few days since its release - and the creatures have even been spotted outside 10 Downing Street, ahead of Theresa May's first appearance as prime minister.