Dragon Quest IX has a feature called tag mode in North America, which passively transfers data like treasure maps and player stats wirelessly. As long as your Nintendo DS is on and Dragon Quest IX is in it you can share data, even if you’re just walking around town.
As of March 4, tag mode has been used 117,577,073 times and that makes Dragon Quest IX: Sentinels of the Starry Skies the most popular ad-hoc wireless game… ever. Square Enix super tweeter Shinji Hashimoto posted a picture of the certificate over Twitter. That number is sure to go up when Nintendo publishes Dragon Quest IX on July 11 in North America and July 23 in Europe.