Broken Sword: The Smoking Mirror is a 2D adventure game played from a third-person perspective. Via a point-and-click interface, the player guides protagonist George Stobbart through the game's world and interacts with the environment by selecting from multiple commands, while Nicole Collard is also a playable character in selected portions of the game. The player controls George's movements and can engage in dialogue with other characters through conversation trees to gain hints of what needs to be done to solve the puzzles or to progress the plot. He also have to collect objects that can be used with either other collectible objects, parts of the scenery or with other people in order to solve puzzles and progress in the game. By right-clicking on an object, the player gets a description and clues. The player character's death is possible if he makes a wrong decision.

Several months after the events of The Shadow of the Templars, George Stobbart and Nicole Collard visit an archaeologist named Professor Oubier to learn about a mysterious Mayan stone for a newspaper story, but soon caught in another conspiracy.