Shamrocks Solitaire is my favorite pile based card game. The trick to the game is that you can't have more than 3 cards in any pile. This makes the game a bit difficult to get started, but once you get going, it's pretty fun. Aside from the 3 card rule, the rules for building on the piles is pretty loose. You can build the piles up or down, without regard to suit. What that means, is that the card you want to move onto another pile is legal as long as the card is one more than or one less than the card currently on the top of the pile (and there are 2 or less cards currently in the pile). Another thing that makes it a little tricky is that once all the cards are removed from a pile it is gone for good and can't be restarted.