SUWON, South Korea  Neither had a job. They were shy and had never dated anyone until they met through an online chat site in 2008. They married, but they knew so little about childbearing that the 25-year-old woman did not know when her baby was due until her water broke.

But in the fantasy world of Internet gaming, they were masters of all they encountered, swashbuckling adventurers exploring mythical lands and slaying monsters. Every evening, the couple, Kim Yun-jeong and her husband, Kim Jae-beom, 41, left their one-room apartment for an all-night Internet cafe where they role-played, often until dawn. Each one raised a virtual daughter, who followed them everywhere, and was fed, dressed and cuddled  all with a few clicks of the mouse.

On the morning of Sept. 24 last year, they returned home after a 12-hour game session to find their actual daughter, a 3-month-old named Sa-rang  love in Korean  dead, shriveled with malnutrition.

In South Korea, one of the world’s most wired societies, addiction to online games has long been treated as a teenage affliction. But the Kims’ case has drawn attention to the growing problem here of Internet game addiction among adults.