You are the Codebreaker and your mission is to break the Codemakers codes (and also to become the Codemaster), via the Decoding Board (6 x 6 grid in the middle of the screen) you set the color selected from the Decoding Palette (below the 6 x 6 grid). When done selecting a code, in the Decoding Board, that you want to use to break the code, then press the "GO!"-button. In the Code Validator (to the left of the "GO!"-button), you will see the results of the last checked code.
Code Validator results:
Black color = wrong color.
Red color = right color more...