Code Breaker
A compact logic puzzle with no timer pressure. Find a secret four-digit code using the feedback from each guess: exact matches have the right digit in the right position, while misplaced matches belong elsewhere. Every digit in the code is different, including a possible leading zero, and you have eight careful guesses to solve it.
No personal best yet — finish a run to set one.
Guesses
—
Score
—
Find a secret four-digit code. Every digit is different, and zero can come first. After each guess, the clues tell you how close you are.
How to Play
- 1.Press Start to generate a secret four-digit code with no repeated digits.
- 2.Enter four different digits for each guess; a leading zero is allowed.
- 3.Exact counts digits in the right position; misplaced counts correct digits in another position.
- 4.Use the clues to narrow the possibilities over up to eight guesses.
- 5.Solve the code for a score of 9 minus your guesses used.
Use this as a personal practice score
Results can vary with your device, browser, input method, and the specific round. They are useful for comparing your own runs under similar conditions, not for clinical, hiring, or diagnostic decisions. Read the methodology.
How Code Breaker works
Code Breaker asks you to discover a four-digit secret. Each digit is unique, digits come from 0 through 9, and a leading zero is allowed. You receive eight valid guesses; every guess must also contain four distinct digits.
After each guess, the game reports exact-position matches and correct digits placed in the wrong position. Those counts are clues, not a list of which digit belongs in each slot. Keep a small written grid if you want to avoid repeating an eliminated possibility.
A worked code-breaking example
Use the teaching secret 0472. The guess 0123 returns 1 exact and 1 misplaced: 0 is exact, 2 belongs elsewhere, and 1 and 3 are absent. Rotating those same digits to 1230 returns 0 exact and 2 misplaced. The split changed, but the total stayed two.
Exact plus misplaced cannot change when you only reorder the same guessed digits, because the set of guessed digits did not change. A rotation tests positions; replacing at least one digit is required to test new membership. Use each guess to answer one declared question.
Scoring and practice
A solved code earns 9 minus the number of guesses used: solving on the first guess is 8, and solving on the eighth is 1. An unsolved code scores 0. This is a puzzle score, so compare attempts by how efficiently you used clues rather than against a population benchmark.
Practice three slow games and name the purpose of each guess before submitting it. Review whether a loss came from ignoring a constraint, retesting the same idea, or using too many guesses to identify digits.
Frequently asked questions
Can the secret start with zero?
Yes. Zero is one of the ten possible digits and may appear first.
What makes a guess valid?
It must contain exactly four distinct digits.
What happens after eight guesses?
The game ends. A win scores from 8 down to 1 based on guesses used; an unsolved code scores 0.
More Skill Games
Visual Search Test
Free visual search test. Find the odd symbol hidden in a grid of look-alikes across five rounds — measuring scanning speed and click accuracy.
Stroop Test
Name the ink color, not the word — the classic interference test of focus and cognitive control, scored on speed and accuracy.
Go/No-Go Test
Free go/no-go test. React fast to green, hold back on red — the classic impulse-control task, scored on go reaction time and inhibition errors.