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Categories:  Abstract Games Decamentathlon Psychological Games Traditional Games

Mastermind sometimes called Code Breaker is not the Quiz show with the black chair and spot light but is the game where the opponent uses information from each of their guesses to try and deduce the hidden code. It is a combination of a Psychological Game and calculation. It is important not to react too strongly to your opponents move until they have completed them. In high pressure situations even marking the code can be demanding with a mistake having cost many a match. The competition is normally played with just 4 slots / holes and 8 colours but the puzzles go as high as 5 slots and 9 colours. It is one of the 10 games in the Decamentathlon.


Mastermind at the MSO is played with 8 colours and 4 holes. No blanks allowed. A guess is made then the setter has to mark the code a red (or black) small peg for each colour that is in the right hole and a white small peg for each colour that is right but in the wrong hole. A repeated colour only gets a white peg if the colour is repeated in the code. For tournament conditions if the setter marks incorrectly when they hit the clock then the guesser counts as having got it right on the next move (or on the mmistake line if the guess was in fact the solution). The code should be set using the coloured pegs from a neutral set and the guesser should wait well away from both the neutral set and the board until summoned. Mastermind problems that have been used as a tie-break in the past can go as high as 5 holes and 9 colours and this is also the case for the Decamentathlon

You can find out about opportunities to play Mastermind live at the timetable. Please report any external links that have broken or have changed to contain inappropriate material. More information about how tournament play works can be found in clocks and in MSO rules.

MSO Mastermind Champions

2012 Dario De Toffoli Italy Olympiad Champion
2011 George Lane England Olympiad Champion
2010 Dario De Toffoli Italy Olympiad Champion
2009 George Lane England Olympiad Champion
2008 Dario De Toffoli Italy Olympiad Champion
2007 George Lane England Olympiad Champion
2006 David Pearce England Olympiad Champion
2005 George Lane England Olympiad Champion
2004 Piero Zama Italy Olympiad Champion
2003 David Pearce England Olympiad Champion
2002 Stephen Rowe England Olympiad Champion
2001 Jan Stastna Czech Republic Olympiad Champion
2000 Bob Coull England Olympiad Champion
1999 Karel Daelemans Belgium Olympiad Champion
1998 Shanker Menon India Olympiad Champion
1997 R. Coull England Olympiad Champion

Full results and other winners can be found in Results.

MSO Mastermind Ranked Players:


  Dario De Toffoli, David Pearce, George Lane, Jan Stastna


  Kenneth Wilshire, Stephen Rowe


  Stephen Gardner

External Links