I found this game before I knew it was associated with a preteen dystopian adventure novel, and while The Keepers trilogy is far from being the next Harry Potter craze, it still looks like it could be a good gift for your young cousins or children. It also makes me want to rewatch the movie From the Mixed-Up Files of Mrs. Basil E. Frankweiler!
As for the flash game of Museum of Thieves, it doesn't appear to follow the novel much -- if at all -- and instead is a massive "spot the differences between these two images" puzzle quest. Since it's targeted at kids it definitely ranks as one of the easiest mind teasers I've ever posted, but what it lacks in challenge it makes up for in quantity. With 32 museum room levels it will keep you busy for a while!
Last Week: Word Dynamo!