Gary Chang stood in the middle of his Hong Kong apartment on a recent Saturday morning, looking at a wall-size screen. He stepped on the balance board of his Nintendo Wii game system for a second run of downhill skiing and began to shift from side to side, moving in time with a computer-generated figure across the room from him.

               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 Sai Wan Ho district – look like an old sepia print.

               He grabbed a handle near the wall-mounted television, pulling a section of the wall itself toward the center of the room. Behind it, a small countertop with [a two-burner stove], a sink and a spice rack appeared. Opposite the countertop, on the back of the now-displaced wallm he lowered a hinged worktop. Suddenly, he was standing in a kitchen.

               This room… and the “video game room” he was sitting in minutes before are just two of at least twenty-four different layouts that Mr. Chang, an architect, can impose on his 344-suare-foot apartment. What appears to be an open-plan studio actually contains many rooms, because of sliding wall unites, fold-down tables, and chairs.

                Mr. Chang, forty-six, has lived in this seventh-floor apartment since he was fourteen, when he moved in with his parents and three younger sisters; they rented it from a woman who owned so much property that she often forgot to collect payment.

               Like most of the 360 units in the 17-story building, which dates to the 1960s, the small space was partitioned into several tiny rooms – in this case, three bedrooms a kitchen, a bathroom and a hallway. Mr. Chang’s parents shared the master bedroom though when they first moved in, his father lived in the United States, where he worked as a waiter at Chinese restaurants in various cities. His sisters shared a second bedroom, and the third, almost incredibly – although not unusually for Hong Kong – was occupied by a tenant, a woman in her twenties, whom Mr. Chang remembers only for the space she took up. Mr. Chang slept in the hall way, on a sofa bed.