.hack (pronounced "dot-hack") is a Japanese multimedia franchise that encompasses two multimedia projects: Project .hack and .hack Conglomerate. Both projects were primarily created/developed by CyberConnect2, and published by Bandai. The series is still ongoing, with a new manga series recently announced.
The plot of .hack is set in the early part of the 21st century. In this world, the Internet has spread across the planet, creating a unified global network which controls everything from the stock market to vending machines. At the center of this network is a popular virtual-reality massively multiplayer online role-playing game (MMORPG) called The World. Players from all around the world play this game, which has been made available in over 20 different languages. However, problems begin to arise when players begin mysteriously falling into comas while playing the game. Each part of the .hack series gives the viewer a different piece of the mystery of The World, which when put together explains what is actually occurring within the game.
Project .hack occurs in the original game The World.
.hack Conglomerate takes place in the sequel to The World, The World R:2.
.hack//G.U. is the title of a series of three video games for the PlayStation 2. The first title in the series, Vol.1 Rebirth, was released in Japan on May 18, 2006 and on October 24, 2006 in North America. Vol.2 Reminisce was released on September 28, 2006 in Japan and on May 8, 2007 in North America. Vol.3 Redemption was released on January 18, 2007 in Japan and on September 10, 2007 in North America.
The games take place after the .hack//Roots anime series. .hack//Roots serves as a prologue to the G.U. video game series in the same way the .hack//Sign anime series served as a prologue to the four original .hack games.