The world of Mohammed al-Musseimi was not very wide. The 15-year-old lived with his aunt and grandmother in a gloomy house almost without windows in the city of Nablus in the occupied West Bank.
Since leaving school a year ago, he had spent his days with his older brother and other teenagers in the Balata refugee camp. Some days, they would play football or swim. On others, they would play PUBG on their phones, an online combat game that pits players against each other.
