Mastermind is a code-breaking game that helps develop deductive reasoning and logic by requiring players to deduce secret combinations of colors with minimal clues. After each of these chances, the creator of the code must reveal how many pegs are the correct color in the correct location, or the correct color in the incorrect location, or completely incorrect. With this little information, the code breaker must improve upon his previous guess to crack the code. Most Mastermind boards give players eight or 10 chances to correctly guess the code before requiring a forfeit.
Assign each player a role. One player must make the code and give clues, and the other must try to break it. Orient the board so that the shielded end faces the player making the code.
A sequence of four colored pegs is chosen by the code maker and placed within the code shield. The sequence can incorporate one to four different colors. Most Mastermind boards include at least six different colors of pegs, which means that not all colors can be played at one time. The code breaker cannot see this arrangement.
The code breaker places four colored pegs in the first row.
The code maker uses key pegs to show the correctness of the guessed pattern. A red key peg indicates that the color is correct, and in the correct position. A white key peg indicates that the color does occur in the sequence, but not in that position. If the color does not appear at all in the sequence, the code maker does not use a key peg. The key pegs are not placed in any way that indicates which color pegs the key pegs correspond to.
Game play continues by repeating steps 3 and 4 until the code breaker correctly guesses the code or all rows of the Mastermind board are filled without yielding a correct answer.
Score the game. The code maker receives one point for each incorrect guess made by the code breaker. If the code breaker can prove that the code maker provided incorrect feedback, the code breaker receives three points and the code maker forfeits all points. If the game is finished without a correct answer, the code maker receives 11 points.