Cut off from the Internet, young Cubans have quietly linked thousands of computers into a hidden network that stretches miles across Havana, letting them chat with friends, play games and download hit movies in a mini-replica of the online world that most can’t access.

Home Internet connections are banned for all but a handful of Cubans, and the government charges nearly a quarter of a month’s salary for an hour online in government-run hotels and Internet centers. As a result, most people on the island live offline, complaining about their lack of access to information and contact with friends and family abroad.