During the Second World War, a catholic priest receives an alarming letter warning about Hitler's plans to find the Lance of Longin, a holy relic rumored to grant mysterious powers to its bearer. The priest decides to travel around the globe, trying to gather all the pieces of the lance before the Nazi army.
Secrets of the Vatican: The Holy Lance is a hidden object game, where most of the time the objective is to search and find all the items listed at the bottom of the screen, on static scenes representing locations around the world filled with assorted objects. After finishing each scene, a new entry is added to the diary moving the plot forward and opening other travel locations. A coin at the bottom-left is the hint button, showing the exact position of one of the required items when activated, but taking some time to recharge after use.
Some of the locations have puzzles that appear on a separate screen. They are usually cryptographic challenges, where the player must set a mechanism using a list of symbols and their corresponding alphabet letters. The game language can be set to English, French, Spanish, German and Italian.