Kim Kyu-min is an admirably dedicated student. Even in his winter break, the 18-year-old goes twice a week to a cramming school, where he has four hours of intensive tuition followed by four more of individual practice until 10pm. In a classroom furnished with desks for 28 students, he sits in quiet concentration as a teacher holds forth. The unusual thing is his subject of choice: not English or maths, but “Valorant", an online game. At Seoul Game Academy, a chain of schools in South Korea’s capital, 3,000 students aged nine and up (roughly 99% of them boys) hone their…