Guilty Gear series takes place around the year 2180, in a chaotic, mystical future world. In 2010, mankind discovered an unlimited energy source of incredible power, which was labeled Magic. Despite providing a solution for world energy crises, wars continued. The power of Magic was combined with the human body creating living weapons known as Gears. Eventually the Gears turned on the human race, beginning a century-long global war known as the Crusades where the Sacred Order of Holy Knights (Seikishidan being the Japanese name), defeated Justice, leader of the Gears. Justice having been locked away in a dimensional prison, all other Gears seemingly ceased to function, bringing end to an age of conflict.

Guilty Gear XX #Reload: The Midnight Carnival, pronounced Guilty Gear XX Sharp Reload, was released in 2003. #Reload was intended to further balance high-level play. Many moves were altered, from slight tweaks in speed and damage to almost complete reworkings in some cases, False Roman Cancel points were added, and notably, Robo-Ky was changed entirely, made playable from the beginning, and considered tournament-legal from then on. In actuality, two versions were released, the first being referred to as "Red Reload." Red Reload contained many errors and was quickly revised and redistributed, this time widely called "Blue Reload."

(Copypasta from English Wikipedia)