It is Zhang Yuchen's last summer break before high school, but events have taken an unwelcome turn -- the 14-year-old's game time has been decimated as China's tech firms try to dispel accusations that they are selling "spiritual opium" to the country's youth.An edict by gaming giant Tencent means players under 12 can no longer make in-game purchases in multiplayer battle smash-hit "Honor of Kings", while under-18s are locked out after two hours during holidays and one hour on school nights."I wanted to cry," an anguished Zhang said as the news ricocheted across the world's largest gaming market, which soaked...