999: Nine Hours, Nine Persons, Nine Doors

999: Nine Hours, Nine Persons, Nine Doors is a 2009 handheld visual novel developed by Chunsoft for the Nintendo DS. Nine strangers awaken trapped aboard a sinking cruise ship, each fitted with a numbered bracelet, and are forced to play the sinister "Nonary Game," escaping through numbered doors within nine hours before the vessel floods.

The game alternates between story-driven visual novel segments, where alliances and mistrust build among the cast, and first-person escape-room puzzle sections in which players examine environments, combine items and solve numerical riddles to unlock the next door. Its heavily branching narrative, multiple endings and clever exploitation of the DS hardware's two screens built toward a genuinely startling, mind-bending revelation.

999 became a cult favorite that launched the acclaimed Zero Escape trilogy of thrillers. It has been remastered and bundled with its sequel for modern platforms, letting a broader audience experience its ingenious, twist-laden narrative and puzzles.