"Sunless Sea" is set in the Unterzee, the name for the ocean in the Neath. The player plays a sea captain who sails (called 'zailing' in the game) the Unterzee. They might 'zail' to make money, to become famous, or for more personal reasons, such as in memory of their dead father. "Sunless Sea" is a computer role-playing game, but it also has some parts from other kinds of games. For instance, it has the roguelike traits that you need to make a new character if you die, and you need to keep track of your food and fuel.