From the publisher's website:

The game takes place over 3 rounds. To start a round, all players simultaneously choose any 1 card from their hands that they would like to keep and place it face-down in front of them. When each player has done this, everyone reveals their chosen cards. After revealing cards, pass your remaining hand face-down to the player on your left. Everyone picks up their new hands and the next turn begins. You now have a new and smaller hand to choose from. When the final remaining card of each hand is passed on, simply place it face-up with the other cards you have collected. (Often this final card won’t be of much use, but sometimes an unfortunate player will be forced to leave you with something valuable!) Now score the cards you have collected. Whoever has the most points after 3 rounds is the winner. In case of a tie, whoever has the most pudding cards wins!