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Guess History0 Guess

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How to Play

System generated a 3-digit unique code.

A: Number & Position correctB: Only Number correct

Example: Code is 1234

Guess 1543 -> Hint 1A2B

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📝 Memo Tap: Exclude (crossed) / Include (green)
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About Classic Codebreaker (Mastermind)

Codebreaker is a deeply challenging and highly addictive logic and deduction puzzle game, heavily inspired by the globally beloved board game Mastermind (and closely related to the classic 1A2B Bulls and Cows game). In this ultimate test of logical reasoning, you step into the shoes of an elite hacker. Your mission is to deduce a hidden sequence of colored pegs within a limited number of attempts, using only the cryptic clues provided by the system. Play free online directly in your browser—no downloads needed!

Basic Rules & The Clue System

At the start of the game, the system generates a secret code consisting of a sequence of colors. You must place your guess in the current row and submit it. The system will then evaluate your guess and provide critical feedback using feedback pegs:

  • Black Pegs (Bulls / Exact Matches): Indicates that one of your guessed colors is not only in the secret code, but it is also placed in the exact correct position.
  • White Pegs (Cows / Partial Matches): Indicates that one of your guessed colors exists in the secret code, but it is currently placed in the wrong position.
  • Empty Spaces: Meaning a guessed color does not exist in the secret code at all.

Crucial Note: The order of the feedback pegs (black and white) does NOT correspond to the positions of the colors you guessed. You must use pure logic to deduce which peg applies to which color!

Advanced Deduction Strategies

To crack the code in the fewest possible moves, wild guessing won't cut it. Master codebreakers rely on strict elimination strategies:

  • The Opening Gambit: High-level players often start with a combination of completely distinct colors (e.g., ABCD) to quickly discover which colors are in play. Another popular opening is AABB, which mathematically helps to quickly filter out large chunks of the candidate pool.
  • Hypothesis Testing: If you receive \"1 Black, 1 White\", you must form a mental hypothesis (or use in-game notes). Assume one specific color is the \"Black\" peg and logically test if the remaining colors can satisfy the \"White\" peg condition without contradicting previous clues.
  • Utilizing \"Dead\" Colors: Don't just focus on the right colors! Colors you have proven to NOT be in the code are incredibly valuable as \"placeholders.\" You can use them in subsequent guesses to isolate and test the exact position of a single suspect color.

X-Game's Exclusive Multiplayer Speedrun

Solving puzzles alone is fun, but we've taken Mastermind to the next level with our exclusive Real-Time Multiplayer Speedrun Mode:

  • Fair Competition: Everyone in the lobby is tasked with cracking the exact same secret code simultaneously.
  • Brain vs. Speed: It’s not just about deducing the answer—it's about doing it faster than your opponent under intense pressure. The first player to successfully crack the code steals the win!
  • Scalable Difficulty: From the welcoming \"4 pegs, no duplicates\" beginner mode, all the way to the nightmare-inducing \"6 pegs, duplicates allowed\" expert mode, we have a challenge for every caliber of logic enthusiast.

Are you ready to put your IQ to the ultimate test? Select your difficulty above and start breaking the code!