Q: What is Mastermind Deduce?

A free code-breaking deduction game. Each round shows a history of past guesses and their black/white peg feedback. Exactly one candidate code is consistent with every row · pick it to build a streak. Miss once and the run ends.

Q: How is the answer validated?

A pure function called verifyFinalDeduction replays the entire history against the full six-colour permutation space (1,296 codes). If your chosen code is the unique survivor · the only code consistent with every row of feedback · the answer is correct.

Q: What do the black and white pegs mean?

Standard Mastermind rules. A black peg means a peg in your guess is the right colour and the right position. A white peg means a peg is the right colour but the wrong position. The order of the pegs in the feedback does not map to the positions of the guess.

Q: Is every round solvable by pure deduction?

Yes · the generator only keeps history rows that actually prune the candidate space, so the puzzle always narrows to exactly one survivor. No guessing required.

Q: Is it free?

Yes, completely free. No account, no ads, no paywalls. Your high streak is stored locally in your browser.