Mastermind is a genuine classic — one player sets a secret code, the other guesses, and every guess comes back with feedback that narrows the possibilities until the code cracks. It's the same core idea behind Bulls and Cows, a pen-and-paper number-guessing game that's been played for generations. Both scratch a very specific itch: pure deduction, no luck involved, just logic tightening with every guess.
Code Breaker is RivalPit's free browser version of that exact idea. It's not Mastermind and isn't affiliated with Hasbro, but the core mechanic — guess, get feedback, deduce, guess again — is the same logic puzzle people have loved for decades.
What Code Breaker plays like
- Guess the hidden sequence. Submit a guess at the secret code and get feedback on how close you were.
- Read the clues. Feedback tells you how many are right value, right position — versus right value, wrong position — the same logic used in Mastermind and Bulls and Cows.
- Narrow it down. Each guess should eliminate possibilities — the fewer guesses you need, the better you're playing.
- Play against a friend or the clock. Race to crack the code first, or just chase your personal best guess count.
No download, no app store, no waiting
Code Breaker runs entirely in your browser at rivalpit.com — open it on desktop or phone and you're deducing in seconds. Try it free as a guest, or sign up to save your stats.
A puzzle that rewards pure logic
There's no luck to fall back on here — every win comes from reading the clues correctly and narrowing the possibilities faster than last time. That's exactly what's kept Mastermind and Bulls and Cows popular for so long.