Each player gets 4 face-down cards. You peek at your 2 front cards at the start.
On your turn: draw from the deck or discard pile, then replace one of your cards or discard it.
Cards are 0–9. 0–5 are cats (good), 6–9 are rats (bad). Lowest total wins the round.
PEEK: look at one of your own cards. SWAP: blind-swap one of your cards with an opponent's. DRAW 2: draw two cards, keep one.
When you think your hand is lowest, KNOCK. Everyone else gets one more turn, then reveal. First to 3 rounds wins the match.