The game was originally developed in 1971 by Merle Robbins in Reading, Ohio, a suburb of Cincinnati. When his family and friends began to play more and more, he spent $8,000 to have 5,000 copies of the game made. He sold it from his barbershop at first, and local businesses began to sell it as well. Robbins later sold the rights to UNO to a group of friends headed by Robert Tezak, a funeral parlor owner in Joliet, Illinois, for $50,000 plus royalties of 10 cents per game. Tezak formed International Games, Inc., to market UNO, with offices behind his funeral parlor. The games were produced by Lewis Saltzman of Saltzman Printers in Maywood, Illinois.
In 1992, International Games became part of the Mattel family of companies.
The aim of the game is to be the first player to score 500 points, achieved (usually over several rounds of play) by being the first to play all of one’s own cards and scoring points for the cards still held by the other players.
The deck consists of 108 cards: four each of “Wild” and “Wild Draw Four,” and 25 each of four different colors (red, yellow, green, blue). Each color consists of one zero, two each of 1 through 9, and two each of “Skip,” “Draw Two,” and “Reverse.” These last three 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 (see restriction below)
- 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:
|Card||Effect when played from hand||Effect as first discard|
|Skip||Next player in sequence misses a turn||Player to dealer’s left misses a turn|
|Reverse||Order of play switches directions (clockwise to counterclockwise, or vice versa)||Dealer plays first; play proceeds counterclockwise|
|Draw Two (+2)||Next player in sequence draws two cards and misses a turn||Player to dealer’s left draws two 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)||Player to dealer’s left declares the first color to be matched and plays a card in it|
|Wild Draw Four/Draw Four Wild (+4 and wild)||Player declares the next color to be matched; next player in sequence draws four cards and misses a turn. May be legally played only if the player has no cards of the current color (see Penalties).||Return card to the deck, shuffle, flip top card to start discard pile|
- 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 Wild Draw Four card. 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.
- 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. 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.
- 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 two 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 Wild Draw Four card, the following player can challenge its use. The player who used the Wild Draw Four 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 four 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.
In a two-player game, the Reverse card acts like a Skip card; when played, the other player misses a turn.
The following official house rules are suggested in the Uno rulebook, to alter the game:
- Progressive Uno: If a draw card is played, and the following player has the same card, they can play that card and “stack” the penalty, which adds to the current penalty and passes it to the following player. (Although a +4 cannot be stacked on a +2, or vice versa.) This house rule is so commonly used that there was widespread Twitter surprise in 2019 when Mattel stated that stacking was not part of the standard rules of Uno.
- Seven-O: When a 7 is played, the person who played may choose to swap their hand with that of another player. When a zero is played, all players pass their hands to the left.
- Jump-In: If a player has exactly the same card (both number and color) as the top card of the discard pile, they may play it immediately, even if it is not their turn. The game then continues as if that player had just taken their turn.