Bulls and cows

Code breaking game
the animal

Bulls and cows (also known as cows and bulls or pigs and bulls) is a code breaking mind or paper and pencil game for two or more players. The game is played in turns by two opponents who aim to decipher the other's secret code by trial and error. Bulls and cows predates the commercially marketed board game version, Mastermind and the word based version predates the hit word game Wordle. A version known as MOO was widely available for early mainframe computers, Unix and Multics systems, among others.

This version is usually played orally, but is easier to play if each player (or each team) keeps written notes. It is exactly like the numerical version, except instead of four digit numbers, four letter words are used. They must be real words, according to whatever language or languages the game is being played in. Alternative versions of the game can be played with three letter or five letter words, but the four letter version remains the most popular one. The game play for the word version is as follows. One player (the host) thinks of an isogram word (i. e. no letter appears twice) and, if the word length is not pre determined, announces the number of letters in the word. Other players (the guessers) try to figure out that word by guessing isogram words containing the same number of letters. The host responds with the number of cows and bulls for each guessed word. As with the digit version, "cow" means a letter in the wrong position and "bull" means a letter in the right position. For example, if the secret word is heat, a guess of coin would result in "0 bulls, 0 cows" (none of the guessed letters are present); a guess of eats would result in "0 bulls, 3 cows" (since E, A, and T are all present, but in the wrong positions from the guess), and a guess of teal would result in "2 bulls, 1 cow" (since E and A are in the right positions, while T is in the wrong position). The game continues until one of the guessers scores "4 bulls" for guessing heat. The word version of bulls and cows is similar to Wordle, a popular web based word game released in 2021. Players have six attempts to guess a five letter word.