How to play Codebreaker
Codebreaker is a deduction game against a hidden code. The code is a row of symbols, and after every guess you are told how close you came — but not exactly where.
Crack the code before you run out of guesses. Fewer guesses and a quicker solve score more.
Rules
- Classic codes are 4 symbols long, drawn from 6, with 10 guesses. Hard codes are 5 long, drawn from 8, with 12 guesses. A symbol can appear more than once in a code.
- After each guess you get one pin per symbol: a solid pin for a right symbol in the right place, a hollow pin for a right symbol in the wrong place. Pins are listed solid first and never say which position they belong to.
- Repeats are counted fairly: a symbol only earns as many pins as it appears in the code.
- A cracked code scores 100 points for every guess left unused (counting the winning one) plus 1 point per second under the time cap — 5 minutes on Classic, 10 on Hard. Hard scores are doubled. An uncracked code scores nothing.
- Daily is a Classic code that is the same for everyone that day. You get one go at it; daily results are saved in your history but kept off the rankings, since a shared code can be passed around.
- Below the board, a counter shows how many codes are still consistent with every pin so far.
Controls
- Click / tap a symbol
- Put it in the next empty slot
- Click / tap a slot
- Clear that slot
- 1 – 8
- Put that symbol in the next slot
- Backspace
- Clear the last symbol
- Esc / Delete
- Clear the whole row
- Enter
- Check the guess (or start a new code when one is over)
- P
- Pause and resume
Tips
- Open with a guess that uses two symbols twice each (on Classic) — it tells you more than four different symbols do.
- Watch the counter: a guess that cuts the possible codes the most is usually a good one, even if it cannot be the answer.
- Before you check, make sure your guess agrees with every earlier row of pins. If it could not be the code, it should at least be teaching you something new.
Codebreaker strategy
A guess is worth 100 seconds
Each unused guess scores 100 points and each second under the cap scores 1, and Hard doubles both, so the exchange rate never changes. A guess you save is worth more than a minute and a half of thinking. The whole time bonus on Classic, 300 points, equals three guesses. Take the extra moment to pick a sharp guess rather than firing off a weak one quickly.
Openings that split the field
Classic has 1,296 possible codes. Two symbols twice each leaves at most 256 after the first row of pins, against 625 for one symbol four times and 312 for four different ones. Hard has 32,768 codes. One symbol five times can leave 16,807, while a spread of four or five different symbols leaves at most around 7,100. On Hard, a second guess built from the unused symbols covers all eight.
Add pins across guesses
The total pins on a row count how many of your symbols are in the code. If two guesses use different symbols, add their totals. On Classic, AABB then CCDD tells you how many of the code’s four are E or F, unless one symbol appears three or more times. A row with no pins at all is the best news there is: every symbol in it is gone from every position.
Close out with the counter
Watch the possible-codes counter, not just the board. While it is large, a guess that cannot be the answer may still split the field better than one that can. Once it is small, play only codes that could win. With two left, guess either. With three, pick one whose pins against the other two would differ, so you win now or know the answer next turn.
About Codebreaker
Hidden-code games are older than the boxed board games that made them famous: Bulls and Cows was played with pencil, paper and numbers before anyone moulded a plastic peg. The pegs-and-pins version became a worldwide hit in the 1970s, and computer scientists have studied it ever since — every Classic code can be cracked in five guesses with perfect play.
This version uses symbols that differ by both shape and pattern, so it plays the same in light or dark mode and for colour-blind players. The daily code is generated from the date, so everyone gets the same puzzle without a server.
Questions
What do the solid and hollow pins mean?
A solid pin means one of your symbols is right and in the right place. A hollow pin means one is in the code but in a different place. The pins never tell you which symbol they refer to.
Can the code repeat a symbol?
Yes. Any symbol can appear more than once, in both Classic and Hard, and pins count repeats fairly: a symbol earns at most as many pins as it appears in the code.
How is the score calculated?
100 points for each guess left unused, counting the one that cracks it, plus a point for every second under the time cap (5 minutes Classic, 10 minutes Hard). Hard scores are doubled.
What is the fewest guesses it can take?
With perfect play, any Classic code (4 symbols from 6) can be cracked in at most five guesses. It takes practice to get close to that.