The official YouTube channel for the Fate/Grand Order smartphone game began streaming an animated commercial for the game's "Lostbelt No. 5 Jindai Kyojin Kaiyō Atlantis" (Atlantis, the Titans' Ocean) story event on Wednesday. The event also debuted on the smartphone game on the same day.
The story event is part of the game's larger "Lostbelt" story line, where the player fights against the Crypters, the betrayer agents of Chaldea, and their effort to replace human history with the failed "Lostbelt" time line.
Aniplex released the Fate/Grand Order game in Japan in summer 2015. The game received an English release in the United States and Canada in June 2017.
Fate/Grand Order Absolute Demonic Front: Babylonia, the television anime of the Fate/Grand Order smartphone game's "Dai Nana Tokuiten Zettai Majū Sensen Babylonia" (Order VII: The Absolute Frontline in the War Against the Demonic Beasts: Babylonia) story, premiered on October 5. "Episode 0 Initium Iter" debuted within the main Fate/Grand Order game app on August 11.
Source: Fate/Grand Order YouTube channel