4 Thrones is a solitaire card game based on a traditional deck of 52 cards. There are four piles (thrones/kingdoms) on which to place all the cards remaining in the deck, one by one. The basic rule of thumb is to place higher cards on lower cards.
The face cards are unique, though, in that they will accept lower cards of certain suits. The Jack accepts a lower card of any suit, the Queen accepts lower cards of hearts or diamonds (love or money, respectively), and the King accepts lower cards that are spades (a soldier's sword).
The game is based on the idea that the four thrones are kingdoms, and you are placing people in power to maintain balance. If you can get through all the cards in the deck successfully, you win.