The series takes place mainly within The World, a fictional MMORPG published and maintained by the also fictional CyberConnect Corporation, known as the CC Corporation. Players interact with The World using virtual reality headsets called HMDs (Head-mounted display) and a gamepad. It is the creation of GermanprogrammerHarald Hoerwick, who creates the first version, "Fragment", to help create his virtual daughter, Aura.
The World consists of a cluster of servers distributed around the world. When players log in, they materialize in the Root Town of the server they last used. Each server in The World has its own unique Root Town. They are the starting and ending point of any gaming session. In order to properly log out of the game, the player must be in a Root Town. Each Root Town has a Chaos Gate, a large revolving ring used to transport players to areas or other servers. To transport to an Area, a series of three keywords must be entered. These keywords determine such parameters as difficulty, terrain, and weather, amongst other habitat. Most keyword combinations result in a field and a dungeon.
In the series' 'Real World', Pluto's Kiss, a virus, caused a simultaneous crash of all computers and network control systems on the Internet that did not run on the ALTIMIT OS, which subsequently became the dominant operating system worldwide. The Twilight Incident, also known as Pluto Again, and the Second Network Crisis is the series of disasters depicted in the .hack//Games. It involves the massive blackout and system shutdown at Yokohama, which results in multiple car accidents, fires throughout the city, various other system malfunctions in other parts of Japan, and various players of The World ending up comatose. It is caused by the glitching Morganna System, though it is eventually resolved with the full awakening of Aura. Kazushi Watarai is held responsible, despite being hospitalized for the majority of the incident.