The player takes on the role of an Unterzee steamship captain, whose background and ambitions are customisable. The player can win by achieving their chosen ambition, such as becoming Fallen London's most celebrated explorer or amassing enough wealth to retire. Resources to achieve these ends are acquired by discovering new locations, trading goods across the Unterzee, battling ships and "zee monsters", and completing "storylet" quests. There are several roguelike gameplay elements, such as partially randomised maps and permanent character death, but subsequent characters can inherit some of their predecessor's possessions, and a player may create a will to ensure lodging and wealth for their successors.