A wall of sound sweeps across the convention floor as ear-splitting music competes with video game effects and booth hosts shouting into microphones. Teenagers in elaborate cosplay weave through the crowd: a princess in a satin pink bodice, metallic heels and long violet hair; a masked warrior in red armor and feathered black wings carrying a plastic assault rifle. Promoters dressed as giant Block Blast puzzle pieces shuffle through the throng as developers clutching swag bags look on.
At one booth, a middle-aged Vietnamese official in a crisp suit and tie stands out against the sea of costumes. He poses ...