Expert Codebreaker is an implementation for Zillions of a game similar to Mastermind, although more difficult. Digits are used instead of colours. The computer chooses a pattern of five digits. In the standard variant it uses digits 1-6. Duplicates are allowed, so the computer could even choose the same five digits. To invoke a random hidden code, press 'Start Thinking'. The chosen pattern is placed upmost but hidden to the player. If you give up and want to view the code, press 'Switch Piece Set'.

The codebreaker must try to guess the pattern, in both order and correct digit, within nine turns. Each guess is made by placing a row of code digits on the decoding board (just press on a square in the lowermost row). Once placed, the program provides feedback by placing from zero to five key pegs at the sideboard. A black key peg is placed for each digit from the guess which is correct in both digit and position. A white peg indicates that a correct digit is placed in the wrong position. The black pegs are always placed leftmost, so there is no correlation of position. Once feedback is provided, another guess is made; guesses and feedback continue to alternate until either the codebreaker guesses correctly, or nine incorrect guesses are made. An inexperienced player can begin at the easiest level where only digits 1-5 are used in the code. You should turn off 'Moves List' in order not to cheat inadverdently .

Mastermind or Master Mind is a code-breaking board game for two players, invented in 1970 by Mordecai Meirowitz, an Israeli postmaster and telecommunications expert. A similar pencil and paper game, called bulls and cows, was played at least as far back as the early 1960's (Wikipedia). With 5 positions and 6 digits, there are 65 = 7776 different patterns. You can try out different solutions by placing a digit on the board. As long as you haven't placed all five of them, you can retract the digit. The standard version, with variants, has also been implemented (see Codebreaker).

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