Gnosia

is a 2019 visual novel social deduction role-playing game developed by Petit Depotto. It was originally released in June 2019 for the PlayStation Vita, and was ported to the Nintendo Switch in December 2020, with a Windows version released in January 2022. It also released for PlayStation 4, PlayStation 5, Xbox One and Xbox Series X/S in December 2023. An anime television series adaptation produced by Domerica premiered in October 2025.

The game's setting takes place on a spaceship in an era where space exploration is at odds with a deadly parasitic disease called gnosia, which seeks to rid humanity by possessing its host. The player takes control of an amnesiac who either chooses to investigate potentially infected crewmates or become one of the infected. At the same time, the player also tries to end a time loop by harnessing the "silver key" inside of them to acquire enough knowledge needed to end it.