Fate/Grand Order (commonly abbreviated as FGO) is a free-to-play PvE turn-based mobile RPG based on the 'Fate' series of visual novels, animes and games. First released in Japan on 30th July 2015, it was later translated to Chinese and released by Bilibili in China on the 10th of September 2016. It was released in Summer 2017 for North America with an official English translation.
The game features an almost visual novel quality story and has a large roster of summonable Servants (based on historical and mythological figures), featuring both original characters and iconic cast members from pervious Type-Moon works.
The protagonist is a newly-appointed member of the Organization for the Preservation of Human Order, Finis Chaldea, an organization of mages dedicated to preserving humanity led by Olga Marie Animusphere. One day, Chaldea is betrayed and most of the mages within are either dead or in critical condition after a series of explosions damages the base. With no other options, the protagonist is forced to "Rayshift" to an unknown timeline along with Mash Kyrielight and Olga to escape the danger. However, Mash is forced to fuse with an unknown Servant to stay alive, turning herself into a demi-Servant with a powerful shield ability.
After the group discovers the traitor, they find that he has used the powers of the Holy Grail created multiple Singularities throughout human history, thus putting humanity on the path to extinction. After the traitor banishes Olga and leaves the rest of Chaldea for dead, Dr. Roman, Mash, and the Protagonist must use what's left to fix the Singularities and stop the traitor from erasing humanity from history.