THIS IS A PART OF EDWARD CHANG'S GGXX PLOT FAQ.
Most of the timeline comes from Drafting Artworks, with additions made by myself based on the GGX novels and drama CDs. Years marked with an asterisk are part of the alternate future time loop created by I-No.
After World War II, the United Nations is founded by many of the nations of the world in order to preserve a global sense of community.
The potential of magic is realized and magic begins to be studied as a science. However the name of the person who first revealed the secrets of magic has been lost.
The "Gear Project", a project dedicated towards the evolution and strengthening of mankind, begins. However its nature and full purpose are unknown.
Frederick, the first prototype in the Gear Project, escaped the laboratory shortly after undergoing the Gear conversion. Along the same time the rest of the laboratory personnel, starting with "That Man", diesappear - the Gear Project grinds to a halt. Frederick, now no longer human, designs a Gear Cell Control Device in order to maintain a human appearance.
That Man completes a "Perfect Gear" archetype, sort of the essence of Justice, that is subservient to mankind. A certain major country restarts the Gear Project. Frederick, learning of That Man's plans, begins designing the Outrage.
That certain major country attempts to use Gears to overwhelm other countries. However, the Gear who possessed his own free will and incredible strength, Justice, had been born. As planned by That Man, other Gears became followers of Justice and turned against mankind. Gears attacked and destroyed the country of Japan. This led to the formation of the Holy Order and the beginning of the Holy War.
A 6-year-old Kliff is saved from a Gear attack by Frederick.
A certain "Sol" is recruited by Kliff into the Holy Order. Eventually, disenchanted by the Order's methods, Sol leaves at an unspecified date, taking the Order's treasured sword "Fuuenken" with him.
At the Battle of Rome, the Holy Order is handed a crushing defeat. Most significantly, Ky Kiske is killed by a Gear. Just before dying, he entreats Sol Badguy to take on the leadership position of the Order.
Johnny is killed in the Holy War. Command of the Jellyfish passes to May. Justice is killed in the Holy War. Embittered, her daughter, Dizzy, takes control of the Gears.
I-No kills Baldhead, who never regained his sanity, and discovers on his body the location of the Gear Plant, which he took from some soldiers he 'operated on'. She gives the information to Sol Badguy. Sol leads an all- out attack on the Gear Plant, but they are no match for Dizzy. Testament kills Potemkin, and Dizzy destroys the Jellyfish and fights with Sol.
Meanwhile, I-No sneaks into the now-abandoned Gear Plant and meets That Man, who is being held captive by the Gears. That Man explains to I-No that he never intended this kind of future when he created Gears.
Intrigued, I-No uses her power to jump through time to return to 2173 and change history.
I-No arrives back in time at the Battle of Rome and saves the life of Ky Kiske. She then erases his memory (?) and officially joins That Man.
With the sealing away of Justice, the long Holy War comes to an end. The Holy Order is disbanded and mankind lives in peace. (AKA Justice's Story Mode in Guilty Gear XX)
Unease spreads around the world as rumors of a "Justice Revival" spread. To quell the rumors and prepare for the worst, the countries form the Second Holy Order and sponsor the Second Holy Order's Fighting Tournament (AKA the first Guilty Gear game). Justice is destroyed by Sol and other Gears lose their ability to act.
The Blackard incident (Lightning the Argent) occurs, and a Gear with free will known as Solaria is created by the company. However, Ky stops their plan of using her as a command-type Gear, and she lives peacefully as a human under the auspices of the Police force.
Rumors spread that in A Country a Gear with free will is found.
Panicked countries sponsor another fighting tournament with a bounty of 50,000,000 World Dollars to whoever can eliminate this Gear (AKA Guilty Gear X). Sol defeats the Gear, Dizzy, but does not kill her. Ky meets her soon afterwards and similarly does not kill her. Dizzy meets Johnny and is adopted into the Jellyfish pirates. Dizzy is "officially" dead and Jam claims the bounty.
A few weeks later a servant of That Man known as I-No begins stirring up trouble... (AKA Guilty Gear XX).
Events from The Butterfly And Her Gale occur. Chipp Zanuff finally gets revenge against the man who killed his master, Volf of the Assassins. Serving as the bodyguard of the President of the A Country (formerly the US), Erica Bartholomew, Chipp helps to pass an official cutting-of-ties between A Country and the Assassin Syndicate. A Country also allies with Zepp.