Halloween Calculation is a solitaire card game with a fun Halloween theme. When you play calculation, you're trying to order cards into calculation piles on the right side of the game screen, skipping numbers based on the card to the left of the pile. The pile with an Ace next to it only needs cards in Ascending order 2,3,4...

The card with the 2 next to it requires every other card 4,6,8... All 4 of these piles are built up without taking suit into consideration. I put the next number that will go into the pile to the left of it, if the procedure isn't completely clear. There are also 5 piles on the top of the game screen. You can place cards in these piles in any order you like, but you have to take the cards off in the opposite order you put them on. In other words, you have to take off the last card you placed on the pile before you can remove the ones below it. You can't move these cards between the 5 piles on the top, and when you take a card off the deck you have to either place it into one of the four piles to the left (if possible) or on to one of the piles on the top. The strategy in the game is entirely in the order of the placement of the cards into these top 5 piles.