The Ultimate Game Environment: Darkness

When playing Deep Sea, the player wears a mask that plunges them into complete darkness and tasks them with carefully listening to instructions and responding with the aim of killing an invisible sea monster:

The sense of being surrounded by invisible dangers is reinforced by the reality of playing the game in a public space, with the player knowing that all around are people they can neither hear nor see. At the same time spectators can watch the gyrations of the player’s body and hear their voice but have no access to the world the player is experiencing, and so remain helpless to rescue the player from their watery fate.