"Leviathan: The Last Day of the Decade" is a detective story told by a dweller of a cruel dark fantasy world affected by the pandemic. The world ruled by a 5 noble-born kins under the suzerainty of the undead Plague King. The player reads through the story and makes decisions at certain points. Solving puzzles will progress the player through the story line. Good or evil actions will influence game play and lead to different endings.