Dueling Network (commonly abbreviated DN) was an online, unofficial Adobe Flash–based simulation of the Yu-Gi-Oh! Trading Card Game (TCG). It was created by Christopher Salvarani on March 3, 2006 and officially released on May 17, 2011. Its popularity grew quickly and it had gained more than four million registered users. The site was run by in-game volunteer administrators and moderators. At its peak, its server allowed for more than 10.000 players to be online at the same time.