buck
BigFishGames is running a special promotion on this game "Hidden Mysteries: Buckingham Palace". Use coupon code buck to buy this game for $0.99 USD, valid for both new and existing users.
1st Runner-Up Best Travel Adventure Game of 2008!
In Hidden Mysteries ™: Buckingham Palace you must peel back the curtains on one of the grandest buildings in the western world to look for treasure and uncover its deepest secrets. Learn fun facts about several royal locations while you search for hidden objects and play ingenious mini-games. Follow romantic notes strewn across beautifully rendered scenes in this exciting sequel to Hidden Mysteries: Civil War.
It is available in both PC and Mac (Mac version here). You can watch the trailer on YouTube, and there's also a 60 minute free trial.