It is a Halloween variation of Solitaire. You need to pass all 100 levels. Use jokers and other bonus cards to simplify the process. You can get the bonus cards by clicking on the ghosts and other spooky characters.
You have to draw cards one at a time from your stockpile. Select the cards that are higher or lower in value to your drawn card to remove it from the playing field. To complete a level you need to remove all the cards from the playing field without running out of cards from your stockpile.