Many in China’s gaming industry agree that games have some downsides. The most popular games in the country are made for smartphones and are free to play, meaning the businesses making them live and die based on how well they draw users in and get them to pay for extras. The game makers have become experts at hooking players. But top-down attempts to wean children off games — what state media has called “poison” and “spiritual pollution” — have sometimes been worse than the problem itself. Boot camps fond of military discipline have proliferated. So have Chinese media accounts of...