Osmosis (also known as Treasure Trove) is a solitaire game played with a deck of 52 playing cards where the object, like many solitaire games, is to put the cards into foundations, although not in numerical order.
Game play consists of four, vertically arranged reserve piles of four cards each (one face-up card on top of three face-down cards). A seventeenth card is put in the first (top) of four foundations, which are also arranged vertically to the right of the reserve piles. Cards with the same suit as this card must be moved to this foundation. The other three foundations are also built by suit, but must begin with cards of the same rank as the first card of the top foundation (the 17th card previously mentioned). Foundation piles are fanned from left to right. All undealt cards make up the stock.
To begin, the top cards in each reserve pile are the only cards in play and must be moved to the foundations if possible. A card can be moved to a foundation if a card of the same value has already been placed in the foundation above it. Once all possible cards have been placed in the foundations, the next face-down cards remaining in the reserve piles are turned face-up. When placing cards from the reserve piles is no longer possible, one can use the stock, deal three cards at a time, and use its top card to make possible moves. One can redeal the stock as long as there are possible moves from the stock or from the reserve piles to the foundations.
Here's an example (foundations only):
| ♥ | 7 8 10 2 4 9 K A |
| ♠ | 7 A 8 K 9 |
| ♦ | 7 8 K |
Suppose that from the example above, any heart card can be moved to the top foundation. One can also place 10♠ into its foundation, but one cannot put 2♦ yet into its foundation because 2♠ hasn't turned up yet in its foundation. No club can be placed at this time as the 7♣ hasn't appeared.
The game is won when all cards have been moved to the foundations. But winning any game relies on where cards are positioned in the reserve piles and in the stock pile. Because of this, finishing a game of Osmosis can be difficult.
Peek is another solitaire card game using a deck of 52 playing cards. It is played exactly as Osmosis except all the cards in this game's reserve piles are face-up.