The aim of the game is to be the first player to discard all of your cards. The deck consists of 108 cards: 4 each of "Wild" and "Wild +4", and 25 each of four colors (red, yellow, green, blue). Each color consists of one zero, two each of 1 through 9, and two each of "Skip", "+2", and "Reverse". These last 3 types are known as "action cards". To start a hand, seven cards are dealt to each player, and the top card of the remaining deck is flipped over and set aside to begin the discard pile. The player to the dealer's left plays first unless the first card on the discard pile is an action or Wild card (see below). On a player's turn, they must do one of the following: - Play one card matching the discard in color, number, or symbol - Play a Wild card, or a playable Wild Draw Four card - Draw the top card from the deck, then play it if possible Cards are played by laying them face-up on top of the discard pile. Play proceeds clockwise around the table. Action or Wild cards have the following effects: Skip: Next player in sequence misses a turn Reverse: Order of play switches directions Draw 2 (+2): Next player in sequence draws 2 cards and misses a turn Wild: Player declares the next color to be matched (may be used on any turn even if the player has matching color; current color may be chosen as the next to be matched) Wild Draw 4/Draw 4 Wild/Draw 4 (+4 and wild): Player declares the next color to be matched; next player in sequence draws 4 cards and misses a turn. May be legally played only if the player has no cards of the current color. A player who draws from the deck must either play or keep that card and may play no other card from their hand on that turn. A player may play a Wild card at any time, even if that player has other playable cards. A player may play a Wild Draw Four card only if that player has no cards matching the current color. The player may have cards of a different color matching the current number or symbol or a Wild card and still play the +4. A player who plays a +4 may be challenged by the next player in sequence to prove that their hand meets this condition. If the entire deck is used 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 another player. A player who plays their next-to-last-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 the other players. If a +2 or +4 card is played to go out, the next player in the sequence must draw the appropriate number of cards before the score is tallied. If a player does not call "uno" after laying down their next-to-last card and is caught before the next player in sequence takes a turn (i.e., plays a card from their hand, draws from the deck, or touches the discard pile), they must draw 2 cards as a penalty. If the player is not caught in time (subject to interpretation) or remembers to call "uno" before being caught, they suffer no penalty. If a player plays a +4, the following player can challenge its use. The player who used the +4 must privately show their hand to the challenging player, in order to demonstrate that they had no matching colored cards. If the challenge is correct, then the challenged player draws 4 cards instead. If the challenge is wrong, then the challenger must draw six cards; the four cards they were already required to draw plus two more cards.
