The goal is to be the first player to get rid of all his cards.
I Doubt It is excellent for children - and even for adults or for mixed groups - because it is easy to learn and can be played either haphazardly or scientifically. It can also be hilarious, especially when eight or ten players are participating in the same game.
Counting and number sequencing.
Four or fewer players should use one standard 52-card pack. Five players may use either a single or a double pack. Six or more players should use a double pack - two standard 52-card decks (104 cards) shuffled together.
The players draw cards from a shuffled pack spread face down. The player with the highest card deals first. Anyone may shuffle, and it does not matter whether the cards are cut or not.
The dealer gives two or three cards at a time to each player in rotation beginning on his left. On the last round of dealing, the cards are dealt out one at a time as far as they will go.
Cards have no actual value but are played in sequence with aces first, then twos, then threes, and so on.
The player on the dealer's left places from one to four cards, face down on the table. As he puts them down, the player announces that he is putting down as many aces as the number of cards. For example, the player may put down three cards, saying, "Three aces." However, the cards need not be aces; the player does not have to tell the truth!
Any player at the table may then say "I doubt it," in which case the cards must be turned up. If the player's statement was true (if, as in this case, all three cards were actually aces), the doubter must take up those three cards and all other cards that have been played on the table previously, into his hand. If the announcement was false in any respect, the player who didn't tell the truth must take all the cards on the table, including those just put down, into his hand. If two or more players doubt the announcement, the one who spoke first is the official doubter. If two players doubt simultaneously, the one nearest to the player's left is the official doubter.
When an announcement is not doubted, the cards remain face down in front of the player until, by the rules of the game, some player is compelled to pick them up and add them to his hand.
After the first player's announcement either has been doubted or not, the player on his left must put down one to four cards and announce that he is putting down that many twos. Next, the player to his left must put down and announce so many threes, and so on around the table. When a player in turn has announced kings, the next player starts over with aces again.
When a double pack is being used, a player may lay down any number of cards from one to eight. The principle is that a player must be permitted to put down every card of a group if he holds it: four of a kind with a single pack or eight of a kind with a double pack.
It is quite ethical to make false statements. For example: When it is someone's turn to play sevens, saying "No sevens,"is a normal part of the game, even if that player has one or more sevens.
When a player puts his last card on the table and either is not doubted or, upon being doubted, is shown to have announced correctly, he wins the game. If the game was played for points or chips, the other players pay the winner 1 point or 1 chip for each card remaining in their hands.
There is no penalty for a misdeal. Any irregularity in dealing should be corrected by adjusting the number of cards in the respective hands, even if the players have looked at them.