Societys obsession with video and online gaming has advanced to the point that virtual environments are indistinguishable from physical ones.

Web developer Josh Weinstein has created Random Dorm, which takes the environment of the highly popular video chat service Chatroulette, and limits it to college students.

Average sales per square foot at American malls, a closely watched measure of retailers' productivity, peaked in 2007 at $454, according to research firm Green Street Advisors Inc. By the end of 2009, the average had fallen to $401, wiping out five years of progress.

For many retailers, the decline has been even steeper. Between 1999 and 2009, sales per square foot at Gap, the country's largest apparel retailer, fell 40% to $329. Total square footage for the company, which also owns the Banana Republic and Old Navy chains, jumped 62% over that period, even though its number of stores increased just 2.6%.

Some of the stores that now run to 18,000 square feet could be just as productive cut to 8,000 to 12,000 square feet, she says.

"Quite frankly, it's just not as positive of a shopping experience as a smaller box that's a more intimate experience," Ms. Simmons says.