Mastermind

The codemaker secretly arranges 4 colored pegs from 6 available colors (duplicates allowed). The guesser has a decoding board with rows for guesses and small holes for feedback pegs.

Codebreaker wins by matching the exact code within the guess limit. Codemaker wins if the guesser fails to crack the code.

The codemaker creates a secret 4-peg code using any combination of the 6 colors. The guesser places 4 colored pegs as their first guess. The codemaker provides feedback: a black peg for each correct color in the correct position, a white peg for each correct color in the wrong position.

Start with a guess using 4 different colors to maximize information. Track your guesses and feedback carefully - elimination is key. If you get black pegs, keep those positions and test other colors.

Mini: 4 colors, 3 pegs (easier, good for children). Super: 8 colors, 5 pegs (much harder). Numbers: Use digits 1-6 instead of colors (good for digital versions). No duplicates: Easier variant where each color appears only once in the code.

Mastermind was invented in 1970 by Mordecai Meirowitz, based on an earlier pencil-and-paper game called Bulls and Cows. It has sold over 50 million copies worldwide.