Purim is a cooperative card-management and area-control game. You and your fellow messengers must work together to spread the King's proclamation, represented by gold cubes, to all the far-flung provinces of the empire. At the same time Haman's ten sons are trying to orchestrate the destruction of the Jewish people by spreading their false messages, represented by black cubes.
Every round each player will receive a set number of Action Cards that have a Loyal Action, an Evil Action, and an End Effect. Players simultaneously select one Action Card from their hand and then reveal it. The Action Cards are then processed based each card's number with the card's Loyal Action happening first before the Evil Action. Loyal Actions will generally add gold cubes to the board, move Messengers, or remove Sons of Haman while Evil Actions will generally add black cubes or move the Calendar tile forward. This process of selecting and playing Action Cards repeats until all but one card has been played in each player's hand. When this occurs the last cards are revealed and the cards processed in numerical order with only the End Effect happening. The round then ends and a new round begins.
The game end triggers when either the Calendar tile reaches the end of the Calendar, or players run out of gold or black cubes. If each Province has gold cubes equal to or greater than the number of black cubes, the players win the game. If even one Province has more black cubes than gold cubes, the players have failed the King and lose the game.