This simple online mastermind game is purely a programming experiment, i.e. a 'pet project' to learn javascript, jquery and jquery-ui. Therefore the mastermind game implementation is the simplest possible mastermind game: no empty slots, no duplicate colors. Perhaps I may modify the mastermind game implementation, but currently I (and my kids) prefer the easier version. Play this mastermind game when in the mood for a casual online game. The mastermind game requires javascript to be enabled, otherwise the game does not work. On a desktop computer you can use drag and drop to move the color pins. On a smartphone or ipad you need to use the controls to place colors.