A color code-breaking logic game: crack the hidden four-gem code in ten guesses. Read the black-and-white peg clues, outsmart sneaky duplicate colors, and chase a personal cracking streak.
About Code Breaker
Code Breaker is a quiet kind of tension: a secret arrangement of four colored gems sits hidden behind the board, and every guess earns a small verdict instead of an answer. A black peg means a color in exactly the right spot. A white peg means a color that belongs in the code but landed somewhere else. Nothing more, no matter how much you want it explained.
The real game happens between guesses, in the deduction. Duplicate colors complicate the count in ways that reward careful logic over lucky taps, and each row narrows the possibilities a little further until the pattern clicks. Pick No Repeats for a gentler climb, or Repeats Allowed with an optional eighth color for Expert players who want the math to bite harder.
It suits anyone who likes puzzles that reward patient reasoning over speed: quick enough for a coffee-break round, deep enough that a clean crack in three or four guesses feels genuinely earned.
Where Code Breaker comes from
Colour code-breaking with black and white clue pegs is the game Mastermind, devised in 1970 by Mordecai Meirowitz, an Israeli postmaster and telecommunications expert, and released by Invicta Plastics of Leicester in 1971-72; it is a peg version of the much older pencil-and-paper game Bulls and Cows, which had already been programmed as MOO at Cambridge by Frank King before the summer of 1970. Four pegs from six colours give 1,296 possible codes, and in 1976 Donald Knuth showed that any of them can be broken in five guesses or fewer. Mastermind is a trademark held by Invicta Plastics and licensed to Hasbro and Pressman; Code Breaker is 360 PlayZone's own browser take on the concept, not the licensed product. Source.
Inside Code Breaker: what we checked
The numbers below come from Code Breaker's own source code, and the screenshots are from our own test run of the game (20 October 2026).
- The code is 4 colours and you get 10 guesses. By default colours cannot repeat, which gives 360 possible codes from 6 colours. Allowing repeats raises it to 1,296, and 8-colour Expert mode to 1,680 without repeats or 4,096 with them.
- Pegs are scored the standard way: a black peg for each right colour in the right slot, then a white peg for each remaining right colour in the wrong slot. A repeated colour in your guess earns a white peg only as many times as it really appears in the code.
- The pegs do not say which slot they refer to, so the order of the black and white pegs tells you nothing.
- Keys 1 to 6 (1 to 8 in Expert) drop a colour into the next slot, Backspace removes the last one and Enter submits.
- Right-click or long-press a colour in the palette to mark it eliminated, as a memory aid. It is only a mark and has no effect on the code.
- Your current win streak and best streak are kept in this browser. Running out of guesses resets the streak to zero.
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How to play Code Breaker
Pick colors from the palette to fill the four slots in your active row, then submit to see your peg feedback. A black peg means right color, right spot; a white peg means right color, wrong spot. Use those clues to narrow down the secret code before your ten rows run out.
Controls
Desktop: click a palette color (or a slot, then a color) to place it, press 1-6 or 1-8 for quick picks, Enter to submit, Backspace to undo, right-click a color to mark it eliminated. Touch: tap to place and submit, long-press a color to mark it eliminated.
Tips & tricks
- Open with a guess that uses several different colors just to see which ones actually appear in the code.
- White pegs matter as much as black ones - do not ignore a color that is right but sitting in the wrong spot.
- In Repeats Allowed mode, do not assume every peg points to a different gem in your guess.
- Mark a color as eliminated the moment you are sure it is not in the code - it keeps your later guesses honest.
Frequently asked questions
Does Code Breaker save my progress?
Partly. Code Breaker keeps a running win/loss tally and your settings in this browser's local storage; there is no level progress to save. Nothing is uploaded and no account is involved — clearing your browser data is what resets it.
Is Code Breaker unblocked at school or work?
Code Breaker is a plain web page of about 28 KB — no plugin, no installer, no app store — so it loads on a Chromebook or a locked-down school or office laptop the same way any other page does, and the whole game arrives in one short download. Whether it opens comes down to your network's filter rather than the game itself.
Who made Code Breaker?
Code Breaker was built in-house by the 360 PlayZone team using open web technology (HTML5), which is why it runs instantly without any download.