Worldwide sales, said a company spokesman, have surpassed 15 million units.
The Pocket 20Q now has several genre-specific variations, including 20Q Movies, 20Q Sports and 20Q Junior for kids.
The devices work through an artificial intelligence program developed by Robin Burgener, Burgener developed the game in 1988, and back in those days, he was running it from a computer floppy disk.
In 1996, Burgener opened a Web site - www.20Q.net. Sometime in the next few days, players will have played 20 Questions on the Web site more than 46,000,000 times.