Cats are unpredictable: one moment enthusiastic, the next bored, then playful again. In this game, players try to change the moods of their cats quickly via simultaneous card play. 

Each player receives three or four stacks of four cards, depending on the number of players. On the cards, you can see cats in thirteen different moods: sometimes winking, sometimes friendly, sometimes grinning widely. Your goal is to have only cards of a single mood in each stack.

Once a round begins, all players simultaneously exchange exactly one card from one of their stacks with a card from the center of the table; exchanging cards from one stack to another is forbidden. 

As soon as a player has collected four identical cards in each of their stacks, they shout, "Stop!" to end the current round. Everyone then reveals their stacks, and for each stack with four identical cards, the owner of that stack scores 1 point. The player who ended the round scores 1 bonus point as long as they didn't make a mistake; if they did, they score 0 points for the round. The game ends as soon as a player has reached 20 points, and whoever has the most points wins!