Chronology

Lore

The story of .hack takes place in an alternate timeline to our own. At the time of release, the most entries of the series were set in the near future. While similar to our reality, several key events differentiate the history of .hack's world from our own.
Near the turn of the 21st century, a catastrophic computer virus wipes out most of the internet and forces world leaders to restrict access to regular citizens. In the following years, only governments and some businesses are allowed use the remaining network infrastructure. The ALTIMIT OS (Altimit Operating System) is released to ensure greater security and avoid future security threats. Over time, citizens are allowed to access the new network and it becomes widely adopted, gaining 100% of the market share for all computer systems around the offline world in everyday applications and use; from desktop computers, government systems, schools, phones, transportation networks, municipal and hospital systems.
A company known as CyberConnect Corporation, commonly referred to as "CC Corp," takes advantage of the dearth of network games and releases a MMORPG called "The World." As the first network game since the crisis, The World is incredibly popular, gaining over 4.5 million players on its first day before going on to having 20 million players by the time of the events that occur in the first set of games in the series.
The basis for The World was created by a German programmer named Harald Hoerwick, based on an epic poem called The Epitaph of Twilight, written by Emma Wieland. Harald sought to use the game to create the Ultimate AI as the daughter he could never have with Emma after her untimely death. Unbeknownst to CC Corp, the development of the Ultimate AI was integrated with the game and was intrinsically linked with ALTIMIT OS and the network's vital operations upon which the majority of Earth's population now depends. As unexpected factors hinder the Ultimate AI's development, the network gradually becomes unstable and the effects begin blurring the boundaries separating offline and online life.
The shift is gradual enough that initially it can be handwaved away by CC Corp, but the frequency of incidents accelerates past the point of being able to conceal it from the general public. Players start to see strange errors spread across The World. Rumors spread of invincible monsters, unusual abilities, and players falling into a coma while playing the game. Strange incidents escalate to the point regular players start to search for answers as CC Corp attempts to cover up the game's involvement.

By Season

Season 1

Project .hack
(Season 1)

Date	Title	Game Version
2007	.hack//Epitaph of Twilight Novels .hack//Epitaph of Twilight Volume I .hack//Epitaph of Twilight Volume II	frägment
	The World R:1 is released
2009	.hack//AI Buster novels .hack//AI buster .hack//AI buster 2 2nd Character Wotan's Spear .hack//SIGN .hack//SIGN OVA "Intermezzo" SIGN SKT .hack//G.U. Begins .hack//SIGN Chapter 1: Encounter .hack//SIGN Chapter 2: Despair .hack//SIGN Chapter 3: Declaration .hack//SIGN Chapter 4: Catastrophe	The World:R1
2010	Games Tetralogy Vol.1~Vol.4 .hack//INFECTION .hack//MUTATION .hack//OUTBREAK .hack//QUARANTINE .hack//Liminality Liminality: In the Case of Mai Minase Liminality: In the Case of Yuki Aihara Liminality: In the Case of Kyoko Tohno Liminality: Trismegistus
	.hack//Another Birth .hack//Another Birth vol.1//INFECTION .hack//Another Birth vol.2//MUTATION .hack//Another Birth vol.3//OUTBREAK .hack//Another Birth vol.4//QUARANTINE .hack//XXXX .hack//XXXX Volume 1 .hack//XXXX Volume 2 New Novelization 「.hack」 .hack//G.U. Begins .hack// Chapter 1: Infection .hack// Chapter 2: Mutation .hack// Chapter 3: Outbreak .hack// Chapter 4: Destruction .hack// Chapter 5: Quarantine .hack// Chapter 6: Rebirth
2011	.hack//SIGN OVA "Unison"
2013	.hack//AI buster 2 Kamui (AI Buster 2) Rumor (AI Buster 2)
2014	.hack//AI buster 2 Firefly (AI Buster 2) .hack//Legend of the Twilight .hack//Legend of the Twilight Manga .hack//Legend of the Twilight Anime
unknown	.hack//frägment Online✕Offline .hack//MOBILE Vol.1 LGT .hack//GIFT .hack//4koma

.hack//Legacy Flower of Wolves & The Wavemaster .hack//RENA The Blooming Wolf & the Crimson Lightning [[Reflections in the Azure Sky (Manga)}|Reflections in the Azure Sky]]

Welcome to Mireille's Dental Clinic .hack//Present from Mother to Daughter Reasons for Donning the Cobalt Knight Uniform

Season 2

.hack Conglomerate
(Season 2)

Date	Title	Game Version
	.hack//ChupChopCase
2015	The World R:2 is released	The World:R2
2016	First Login .hack//Roots .hack//G.U. Begins .hack//Roots Chapter 1: Welcome to the World .hack//Roots Chapter 2: Forefeel .hack//Roots Chapter 3: Breakup .hack//Roots Chapter 4: Tragedy .hack//Roots Chapter 5: Painful Forest .hack//Roots Chapter 6: Determination .hack//Alcor
2017	.hack//GnU .hack//Cell Original G.U. Games .hack//G.U. Vol.1~Vol.3 .hack//G.U. vol.1 //Rebirth .hack//G.U. vol.2 //Reminisce .hack//G.U. vol.3 //Redemption Online Jack .hack//G.U. Trilogy .hack//G.U. novels .hack//G.U.+
	.hack//4koma Peaco's Story
	.hack//G.U. Returner
2018	.hack//G.U. RAGTIME
	.hack//G.U. Innocent Call
	.hack//G.U. Last Recode .hack//G.U. Begins .hack//G.U. vol.4 Reconnection
unknown	.hack//4koma

Journal of the Dark & Wicked The Duplicate Phenomenon

Season 3

Project Third
(Season 3)

Date	Title	Game Version
2020	.hack//Link .hack//Link manga	The World R:X
2022	.hack//Quantum i(Introduction) .hack//Quantum OVA .hack//Quantum Novel .hack//Quantum+
2023	.hack//Bullet	Unknown (不明)
2024	.hack//Beyond The World Beyond The World: SORA	The World FORCE:ERA
2025	.hack//Versus .hack//Versus: Thanatos Report	VERSUS: The World
2030	Guilty Dragon GuilDra G: A Gag Concept	The World: Armed Conflict
2032	New World	The World: Re-vice age

.hack//bullet: Versus Magician

Timeline by Media

.hack Official Website Timeline

dothack.com Timeline (North America)

AI Buster 2

AI buster 2 Timeline