Alternate-reality games flourish at the grassroots

Rather, it was a very small-scale--and low-tech--version of what is known as an alternate-reality game, an entertainment genre that has grown in popularity in recent years, especially because its traditional use of mixed-media--the Web, cell phones, social media, and others--can allow large numbers of people to play together collaboratively.

http://news.cnet.com/8301-13772_3-10402954-52.html

"It turned out that the intrigue was all part of a day-long mystery concocted by Steele's boyfriend, and involving several of their friends, as part of an elaborate marriage proposal."