Am playing this fab new game. You can play it without spending any money, although I am starting to collect the puzzle cards. And of course, there are helpful discussion boards to push you in the right direction. For one of the puzzles in the trickiest category (silver-bordered cards), for example, the general consensus is that it's a solitaire cipher.
So, of course, I follow a link from this discussion group to bone up on Solitaire, and whose name hits me straight in the face?