Monte Carlo uses a standard 52-card deck (no jokers). To begin the game the deck is shuffled, then dealt face-up, one card at a time, into five rows of five cards each (the tableau), with the remainder of the deck held in reserve for later play.

The object of the game is to remove pairs of cards from the tableau. These cards can be any combination of colors, but must be of the same rank (eg: a 3 of hearts and a 3 of spades), and must be located adjacent to each other in a row, column or diagonal. Note that the removal of a card does not make the two cards beside it "adjacent".

After removing all possible pairs, the tableau must be consolidated, which means that the remaining cards in the tableau must be "backed up" (moved to the left, then up, keeping the original order) to fill in the blank spaces created by the removed pairs. Cards from the reserve are then dealt into the newly-created spaces and the process of removing pairs begins again. The tableau can be consolidated and re-dealt as many times as necessary.

The game is won when the entire deck has been removed, or lost when no more moves can be made.