Mastermind

01Discover the game

Mastermind opposes a coder, which hides a combination of colors, and a decoder, which tries to find it. After each proposal, the coder gives a precise answer, but without saying which color corresponds to what index. The decoder must compare its tests and eliminate combinations that have become impossible.

The overall difficulty is difficult: the rule is short, but interpreting the repeated colors and choosing effective tests requires the method. This chapter follows the Hasbro F6423 edition, with four positions, six colors, ten test lines and black and grey indices. It should not be added the eight colors of another box, nor the limit of nine tests of some travel versions.

02Equipment

Notice F6423 gives a game module with cache, 108 code pieces and 30 key pieces. The 108 code pieces are divided into six colors, 18 of each; the keys are 15 black and 15 grey. The module includes the proposal lines, response locations and score meters.

The large colored pawns represent the code and the essays. The small black or grey pawns give the clues. An empty index location is not a third color: it indicates that there is no other match to report. The colors must be recognized by both players; if necessary, name them or use markers written on a teaching diagram.

03The goal

As a decoder, reproduce exactly the four colors, in the right order, in a minimum of proposals. As a coder, create a code difficult to find, then answer honestly to each essay. The roles are then reversed. The selected edition gives the points to the coder according to the number of tests required: the best total after the two roles wins.

04Prepare the handle

Place the module between you, the cache turned towards the encoder. The key pawns are on its side and the code pawns accessible to the decoder. Choose the first encoder. It secretly places four pawns behind the cache and closes it.

It can use several times the same color. For example, Red–Blue–Red–Green is allowed. All locations of the code must be occupied: we do not use an empty hole as the seventh symbol. The decoder must ignore the code until the end. Once the first trial proposed, the secret code no longer changes.

05Propose a line and answer

The turn of the decoder

Place four large pawns on the first line available. Positions are important: Red–Blue–Green–Yellow is not the same proposal as Blue–Red–Green–Yellow. Leave each proposal on the module to keep the history. You can reuse a color several times in your essays.

The turn of the encoder

First compares the four positions one by one. Each pawn of good color in the right place gives a Black Key. Then, among the pawns not yet counted, look for the right colors in bad places: each one gives a Grey Key. A Pawn Code can produce only one clue.

The small clues are not placed against the position they describe. The encoder groups them into the answer holes without revealing their correspondence. Two blacks and a gray thus mean "two exact positions and another color present elsewhere", not "the first two positions are good".

The rehearsals

If the code contains only one Blue and the test consists of three, only one of these Blues can be recognized. If it is well placed, one black is given; otherwise, one grey. The other two do not give any clues. To do not count twice, mentally mark the exact matches and then bar the colors used in both lists.

Continue until solution

The decoder reads the answer and prepares the next line. The coder answers again. The handle ends when four black clues are obtained, or after the tenth proposal if the code has not been found. The tenth line counts as a real test and can therefore still win the search.

An index error

A false answer can make all of the following deductions inconsistent. Notice F6423 states that if the decoder proves an error of the coder, it immediately receives three points and the coder does not receive any for this wrong handle. Pawns are removed and the same coder creates a new code. For a first discovery, you can choose to correct together without penalty, but announce that it is a learning adaptation.

06An example with two reds

The secret code is Red–Blue–Red–Green. The decoder proposes Red–Red–Blue–Yellow. The first position is exact: one black. Among the other pawns, the Red of the second place corresponds to the secret Red of the third, and the Blue of the third corresponds to the secret Blue of the second: two grey. Yellow is not in the code. The answer is therefore one black and two grey.

If the decoder then tries Red–Blue–Green–Red, the first two positions are correct, and Green and Red are present but reversed: two blacks and two greys. Finally Red–Blue–Red–Green gives four blacks. The coder then reveals his code and scores three points, since three lines were played.

To illustrate these answers, visually separate the proposal from the clues. Do not draw a small black key directly under the recognized column: this would communicate prohibited information. Words or letters in addition to the colors make the example readable even without clearly distinguishing the shades.

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07Points and end of game

The encoder marks one point for each line played, including the one that found the code. A code discovered in the first essay thus returns one point to the encoder; in the seventh, seven points. If the ten lines fail, the encoder receives eleven points: ten for the essays and a bonus.

Then reverse the roles with a new code. When each has been encoded once and once decoder, compare the totals: the largest wins. The notice does not detail any particular split; you can share a tie or agree before the part of a new pair of rounds. Do not simply give the victory to the last decoder because he has found his code.

08Frequent errors

• Prohibit repeated colors while this edition allows them.
• Give two clues for the same pawn.
• Count the right colors before the exact positions and assign the repetitions to the wrong place.
• Align the clues under the right columns.
• Change the hidden code after a test.
• Forget that the winning line also brings a point to the encoder.

09Tips for starting

Take the time to reformulate each answer: "two exact places, another present color, one absent color." Then try to find at least one combination that respects all the old clues. A new essay that already contradicts a certain answer cannot be the code.

Do not necessarily change all the colors at each line: a test should allow you to understand something, not just like a guess. The encoder must also check his answer carefully. At first, do an open exercise handle to learn how to count rehearsals before hiding the real code.