Enter "Clos Luce 1519" as a code at the "Codes" screen under the options menu to unlock all levels.
Enter "Vitruvian Man" as a code at the "Codes" screen under the options menu. Note: This must be used for both Robert and Sophie, as the game will end if either dies.
Enter "Sacred Feminine" as a code at the "Codes" screen under the options menu.
Enter "Phillips Exeter" as a code at the "Codes" screen under the options menu.
Enter "Royal Holloway" as a code at the "Codes" screen under the options menu.
Enter "Apocrypha" as a code at the "Codes" screen under the options menu to unlock all Visual Database entries.
Enter "Et in Arcadia ego" as a code at the "Codes" screen under the options menu. This will unlock all levels (including the M0X Louvre level and the M0X Rosslyn level), all Visual Database entries, the music Orrery, all concept art in Rosslyn, all Louvre paintings that are displayed in the substitution puzzles, and all anagram puzzles in Rosslyn.
Successfully complete the game, then use the rotating solar system model that now appears where the globe was during the main game. You can play music from the game. Examine the sun in the model for a full screen view of the solar system. Go to the room that had the trapdoor in the floor in the main game. Examine the table to see all of Leonardo Da Vinci's invention models that were featured in the main game. Use the trapdoor to go down to the lower room to see concept art.
The code for the box in the shed is 13, 21, 34.
Puzzle 1: Rearrange the "OH LAME SAINT" into "THE MONA LISA".
Puzzle 2: The Mona Lisa code is "Da Vinci Painted those that knew between Bacchus and Uriel lies the clue".
Puzzle 3: The painting puzzle to get the dirt off is First Chitinase, then Dismutase, then Catalase.
Puzzle 4: The six statue puzzle is Venus in the middle, Jupiter on the top, to the right of that Mars, to the right of that, Aeneas, to the right of that Cupid, to the right of that Vulcan.
Puzzle 5: The floor safe puzzle is Sion across the middle.
Puzzle 6: The solution to the cryptogram puzzle in level 7 is "OUTDOORS THE GRACEFUL WATER YOU WILL SEE THROUGH DEDICATION YOU MUST FIND THE KEY"
After completing the game you can enter The Louvre and play "The Louvre Revisted" bonus level. The following are the solutions to the the puzzles on the paintings that represent each of the nine levels of the game:
The Louvre Museum painting: "YOU SHOULD NOT HAVE RUN MONSIEUR SAUNIERE NOW TELL ME WHERE IT IS"
St. Sulpice painting: "THE SISTER MUST HAVE BEEN CALLING PRIORY MEMBERS WHEN SHE WAS ATTACKED"
Normandy Mansion painting: "ITS THE PRINCESS SOPHIE KEY MY GRANDFATHER PROMISED ME"
Bank of Zurich painting: "IT IS THE CRYPTEX THIS IS BASED OFF OF A DESIGN BY DA VINCI"
Chateau Villett painting: "THE LEGEND OF THE HOLY GRAIL IS A LEGEND ABOUT ROYAL BLOOD"
Biggin Hill Airfield painting: "SAUNIERE BROUGHT US TOGETHER TO FOLLOW THESE CLUES FOR A REASON"
Temple Church painting: "SILAS TAKE THE KEYSTONE FROM MR LANGDON TEABING IS OUR HOSTAGE NOW"
Westminster Abbey painting: "TEABING FELT THE TRUTH CRASHING DOWN ON HIM THE GRAIL WAS LOST TO HIM"
Rosslyn Chapel painting: "THE QUEST FOR THE GRAIL IS THE QUEST FOR THE DIVINE IN EACH OF US"