O'NO 99 is a proprietary card game formerly produced by International Games, Inc and based on the public-domain card game 99 but played with a unique deck of 54 cards. The object of the game is to play cards numbered 2-10, while avoiding being the player that brings the sum of played cards to 99 or higher. Similar to the game Uno, O'NO 99 has special cards such as Reverse, Hold, and Double Play cards that can alter gameplay.
Up to eight players may take part. Each player picks a card from the deck, and the player drawing the highest-numbered card is the dealer. This person then deals four cards to each player, and places the remainder of the cards face down in the center of the table to form the draw pile. The player to the dealer's left starts the hand by playing a numbered card face up in the center of the table and announces the number. He must then immediately draw a new card from the draw pile. The next player then plays a numbered card on top of the first player's card and announces the total of these numbers added together. Play continues clockwise around the table in this manner, with players continuously adding to the total until someone causes it to reach or exceed 99. That player loses the hand.
In addition to standard cards numbered 2-10, five special types of cards are present in the deck. These may be used to attack other players or help the player using them.
Subtracts 10 points. Negative totals are allowed; for example, if a Minus 10 is played when the total is 6, the next player faces a total of -4.
Leaves the total unaffected.
Leaves the total unaffected and reverses the direction of play (clockwise to counterclockwise, and vice versa). If only two players are in the game, it has the same effect as a Hold.
Leaves the total unaffected and forces the next player in sequence to take two complete turns. That player may immediately use a Hold or Reverse to force the player after him/her to play twice instead. A player who is required to do a Double Play may use a Double Play card on the second turn, but not the first.
Causes the player using it to immediately lose the hand. Ordinarily, this card merely takes up space in a player's hand; however, since there are four of these cards in the deck, it is possible for one player to end up holding all of them and thus lose the hand on his/her next turn.
If a player forgets or hesitates to draw a card after they have played, the next player may quickly play their card and draw, preventing the player from drawing and thus eliminating a card from their hand. This can greatly harm the player, especially if they are already holding O'No 99 cards. A player may correct their error and draw a card at any point before the next player draws their card, even if that player has already played.
Each player is given three chips to begin the game. The player who loses a hand must surrender one chip; when a player loses a hand with no chips remaining, he/she is out of the game. The last remaining player is the winner.