Master Mind is a code-breaking game. This version is based on the Invicta game from the mid 1970's.

It is also based on "The Computer As Master Mind", an article by Donald E. Knuth in 'Recreational Mathematics'.

To play it, click on one of the coloured glass balls and a copy will be placed in the first position. Continue until the row is filled. Click 'Score' to get a measure of how close the guess is to the hidden code.

A black scoring peg means a colour is correctly placed. A white peg means a colour is present but incorrectly placed. An incorrectly placed colour, if duplicated, will not be scored again unless that colour is used in another non-matching location in the hidden code.

'Clear' resets a row if not yet scored. 'Start' will set a new code immediately for a new game at any time. 'Quit' will end the current game and show the code.

I made a version for the Psion Organiser II XP (or LZ but not CM because the game needs a user-defined graphic). It's in a ZIP file here. To use it you'll need to translate the five OPL files to object code after putting them in the Organiser. I won't explain here how to do that, but I will probably do it as part of a general Organiser code section on this site. The OPL code, combined with the JavaScript file supporting this page, may be of interest to someone wanting to port the game to another system.