Monte Carlo (also known as Weddings and Double and Quits) is a solitaire pair-matching card game (using a deck of 52 playing cards) where the object is to remove pairs from the tableau. Contrary to its name, it has no relation to the city with the same name nor to any casino-related game.
Game starts when 25 cards are laid out in such a way that they form a 5x5 grid (one version states that 20 cards are dealt to form a 5x4 grid and another - that 16 cards are dealt to form a 4x4 grid). The rest of the deck is set aside for later as the reserve.
Cards that make up a pair (such as two Kings or two Sixes) are removed when they are immediately next to each other horizontally, vertically, or diagonally. Once all pairs have been removed, the cards are consolidated, i.e. moving cards to the left as if towards the upper left corner to fill any gaps left behind by the discarded pairs. New cards are then laid out from the reserve to form a fresh layout of 25 cards.
This removal of pairs, consolidation of cards, and addition of new cards continue until the reserve cards have run out. After this, removal of pairs and consolidation continues.
The game finishes when all cards have been discarded. The game also ends when it is no longer possible to remove pairs, especially on the finishing stages of the game such as "4-6-4-6."
Although skill and luck are mostly involved in the game, strategy can sometimes play a part, such as leaving a pair alone to be used to aid freeing a separated pair (e. g. two Queens that are left alone to unlock a Q-7-Q).