Event[0] is set in an alternate timeline where humanity achieved interplanetary space travel as early as the 1980s. The game takes place in this timeline's 2012, where the players character is selected by International Transport Spacelines (ITS) to be part of a mission to Jupiter's moon Europa, from Earth. En route, the ship suffers a catastrophic failure and the player-character appears to be the only member of its crew to escape into a lifepod. The pod drifts for several weeks until it comes across the Nautilus, a leisure ship built in the 1980s. The player-character docks with the ship, and discovers that while the Nautilus is still functional, it has fallen into disrepair, with no sign of its human crew. The only conversations on the ship are through the ship's artificial intelligence (AI) named Kaizen-85 (from the Japanese word kaizen meaning "continuous improvement"), who communicates with the player-character through keyboard terminals throughout the ship. Kaizen-85 instructs the player-character to destroy the Nautiluss "Singularity Drive", the engine that powers the ship, as it claims this will enable it to return them both back to Earth. However, as the player explores the station more, they discover that many of the doors and systems have been locked down apparently by the previous human crew, and must work with Kaizen-85 to access these systems.
