The aim of the game is to be the first player to play all of one's own cards. A player who plays a Wild Draw Four may be challenged by the next player in sequence (see
Penalties) to prove that their hand meets this condition. An illegally played Wild Draw Four card incurs no penalty for its user unless challenged. • A player using a Wild or Wild Draw Four card must declare the new matching color before ending their turn, and may declare the current color if desired. • If the draw deck runs out during play, the top discard is set aside and the rest of the pile is shuffled to create a new deck. Play then proceeds normally. • It is illegal to trade cards of any sort with any other player at any time. A player who plays their penultimate card must call "Uno" as a warning to the other players. The first player to get rid of their last card ("going out") wins the hand and scores points for the cards held by each other player. Number cards count their face value, all action cards count 20, and Wild and Wild Draw Four cards count 50. If a Draw Two or Wild Draw Four card is played to go out, the next player in the sequence must draw the appropriate number of cards before the score is tallied. The first player to score 500 points wins the game.
Penalties • If a player does not call "Uno" while laying down their penultimate card and is caught before the next player in sequence takes their turn (i.e., plays a card from their hand, draws from the deck, or touches the discard pile), they must draw two cards as a penalty. If the player is not caught in time or remembers to call "Uno" before being caught, no penalty applies to that player. This rule is not mentioned in the instruction sheets of modern copies of the game. •
Seven-O: Every time a "7" is played, whoever played it must swap hands with another player of their choice before ending their turn. Every time a "0" is played, all players pass their hands to the next player in the current direction of play, after which play continues normally. == Card and deck styles ==