Based on the works of David Gemmel's Ghost King. In my design of the series, this world follows the form of a stealth-action video game set in mid 17th century France, on the cusp of the Revolution.
The king had been slain by conspirators, and the blame falls upon a middle aged inventor, Culain --in whose veins flows the blood of kings. You play as Culain on a quest to clear his name and bring balance to the Kingdom.
In the Palace Study (The Puzzle Room) -- there are symbols etched all over the place to help solve the cosmic riddle surrounding Dupont's Egg which holds the Bloodstone Ring. The Bloodstone contains an unimaginable amount of power however it requires sacrifices and also corrupts it’s user over time.