Mastermind in brief
Mastermind is a code-breaking game invented in 1970 by Mordecai Meirowitz, an Israeli postmaster and telecommunications expert, and published from 1971 by the British company Invicta Plastics. It draws on a much older pencil-and-paper game, Bulls and Cows, in which players guess a secret number.
One player hides a code of 4 pegs chosen from 6 colours. The other proposes combinations; for each, they receive small black key pegs for pegs of the right colour in the right place, and white ones for pegs of the right colour in the wrong place. You know how many pegs are right, never which ones.
What Mastermind fans enjoy
- Pure deduction: every answer eliminates combinations, with no luck in the feedback.
- The puzzle of aggregate feedback: knowing a peg is right without knowing which forces you to cross-check guesses.
- Economy: finding the code in as few moves as possible, with a strategy.
- A short game: a code is cracked in a few minutes.
Mindo keeps these ingredients. Decrypto and Tusmo keep the guess-and-feedback loop with more precise feedback, and Ondulo pushes deduction towards a different kind of puzzle.
Comparison: what each SIWA game shares with Mastermind
| SIWA game | In common with Mastermind | What changes |
|---|---|---|
| Mindo | 4 colours out of 6, aggregate feedback, 10 tries | Shared daily code, score and jokers |
| Decrypto | A secret code deduced guess after guess | 5 digits, one colour per digit, 6 tries |
| Tusmo | The guess-and-feedback loop | A French word, first letter given |
| Ondulo | Deducing a hidden state from answers | You probe an 8×8 field with waves |
Mindo: the closest to Mastermind
Mindo takes up the Mastermind principle. The code has 4 pegs chosen from 6 colours, and the same colour can appear more than once. You have 10 tries at most; after each one, the game tells you how many pegs are in the right place and how many are the right colour in the wrong place, without saying which.
The differences come from the daily format. The code is the same for everyone that day, and the score out of 1000 points depends on the number of tries and on time. If the 10th try fails, the code is revealed automatically: there is no giving up and no free play. A joker reveals one colour of the code, but every joker caps your score, from 70% of the maximum for the first down to zero for the fourth.
Decrypto and Tusmo: the guess-and-feedback loop
Decrypto swaps the colours for a code of 5 digits from 0 to 9, repeats included, to find in 6 tries. The big difference is the feedback: each digit gets its own colour, right spot, present elsewhere or absent. You therefore know exactly where to look, but there are 100,000 possible codes instead of 1296. After six tries, you can carry on in free play, without points, or reveal the code; a joker reveals a digit.
Tusmo applies the same loop to words. It is a French word game: you know the first letter and the length of a French word of 5 to 8 letters, and each guess colours the letters green, orange or grey. For more games from this family, see our roundup of games like Wordle.
Ondulo: deduction by probing
Ondulo is for those who love Mastermind's reasoning more than its pegs. Four modules, whose shape and colour you know, are hidden in an 8×8 field. You send waves from the edges; each one comes out tinted by the colours of the modules it touched.
As in Mastermind, every answer rules out hypotheses, and the score rewards economy: fewer probes, better score. Place your modules, then validate; a wrong validation costs two probes. Time does not count, only the quality of your reasoning.
One code a day, the same for everyone
Each game changes at midnight, in your local time, and it is the same for everyone that day. The daily leaderboard lets you compare your number of tries and your score.
Everything is free, in the browser, with nothing to download and no sign-up. A free account keeps your streaks and opens the archives so you can replay a missed code.