Cruel is a pile based solitaire card game similar to La Belle Lucie. Cruel has 12 piles of 4, where La Belle Lucie has 18 piles of 3, but instead of shuffling the cards like you do in La Belle Lucie, in Cruel you shift all the cards over back into piles of 4. You can also do this as many times as you want.
Now here's the difference between shuffling and shifting. When you shuffle you pick up all the cards not currently in the foundations, shuffle them, then deal them back into the piles (piles of 3 in the case of La Belle Lucie). When you shift cards, you look to where your pile has less than 4 cards in it, then you take as many cards from the pile to the right as you need to make that pile a pile of 4. So all the cards stay in the same order that they started in,but just move over to the left.