The computer creates a hidden code of four colours. Colours may appear more than once.

Build a four-colour guess and submit it. Exact counts colours that are also in the right position. Colour counts correct colours that belong in another position.

The clues do not tell you which individual pegs they refer to. Use them to narrow down the code. You have ten attempts.

Codebreaker uses the classic codebreaking mechanic commonly associated with Mastermind, with an original NCNB interface and presentation.