The Weekly Tournament is held every week, and its duration is seven days exactly. Games are played for tournament chips, the starting stack of which you are to choose when you first enter the tournament. Upon the end of the competition, the top 20% of the players split the pot (its value depends on the total amount of tournament chips involved in the game), and the very top players receive coins, too.
You cannot buy more chips during the tournament. If you've lost all your chips, you leave the tournament automatically, but you can start all over, entering with as many tournament chips as you want again.
You can leave the game any moment you wish. Once you are back, you will continue the game with the amount of chips you had left over when you took your leave.