GARY CHANG stood in the middle of his apartment on a recent Saturday morning, ignoring a message from his Nintendo Wii on the wall-size screen: “Are you fidgeting? I can’t seem to analyze you.” He repositioned the game system’s balance board, stepped on for a second run of downhill skiing and began to shift from side to side, a computer-generated figure swishing in time with him across the room.

Soon enough, having worked up an appetite, he was ready to move on. He used a remote control to raise the screen, revealing a large yellow-tinted window behind it, filling the room with radiance. “Like sunshine,” Mr. Chang said, though the colorized gray daylight made the view — a forest of apartment towers in Hong Kong’s bustling working-class Sai Wan Ho district — look dusky, like an old sepia print. continue reading