In Parley, set in the Mediterranean region of the 16th century, each player chooses one of six fictional corsair characters at the start of the game, receiving a secret mission from one of six corresponding kings.
Twenty ports are located on a map of the Mediterranean Sea on the game board, with these ports initially not belonging to any country. Four of them are under the protection of the great admirals; the other sixteen ports will each be controlled by three countries at the end of the game. In order to control a port, the countries have to make a successful attack on (or defense of) the port in the port siege.
During the game, there will be one siege for each single port. In each siege, three countries will attack the port while the other three countries are on the defensive. The structure of coalitions is random and different each time. Since the power of the countries are equal to each other, the allies which are supported by the corsairs will be victorious.
The corsairs make their collective decision about which coalition it will support by voting. Naturally each player has to vote according to their secret mission but they cannot make it openly. Because the other players can make blackmail if the secret mission of any player is revealed. If the voting is done openly, their secret mission will be exposed and they will be open to blackmail by other players.
At the end of the game, the country who controls the highest number of adjoining ports will be victorious. Automatically the players who support this country will get the most victory points. However, the successful blackmails have a big impact on the final score as well.