Forty Thieves is probably the most popular solitaire game played with two decks, but it takes a lot of time, luck, and skill to win. Build the foundations up in suit from Ace to King. The tableaus are build downwards by suit, and only one card can be moved at a time. Empty tableau slots can be filled by any card. If play is exhausted, click the deal to upturn the top card; this can be played on any foundation or tableau. Enjoy Playing.