The player controls an unnamed character, a friend of the inventor Cornelius, who has been arrested on suspicion of involvement with the Calamitus, a figure said to intend to destroy Rome. The game begins underneath Cornelius’s workshop, and after entering the workshop the player receives a message about the arrest.

The message names five possible Calamiti: Lucius, a retired soldier and private investigator; Verania, the head Vestal Virgin; Xanthus, one of Gordian’s assistants; Sybil, a prophetess; and Gordian, an architect building his own temple with spare project money.

The player is also told about the Navitor, a machine that allows travel around Rome from the workshop. Once activated, it can pick up and use objects in other places, travel in time, and view the suspects’ diaries. The first task is to find the diaries, which then update automatically.

Each month also brings a quest based on a screenshot, requiring the player to find the location and complete a puzzle or task for more clues or an important object. Events in Rome can be read through the diaries and the city newspaper, and the Navitor may occasionally crash, requiring the player to repair the correct seasonal machine in the workshop.