How to play Criboku
Criboku is a daily logic puzzle built on cribbage scoring. You fill in the missing cards so that every row, column and corner square scores exactly the number shown beside it. Every puzzle has one solution, and you never have to guess — it can always be reasoned out.
The board
The grid holds sixteen cards. Twelve hands are scored on it, and each card belongs to three of them at once:
- the 4 rows and 4 columns;
- the 4 corner squares — each 2×2 block at a corner of the grid. A corner square’s score is printed at that corner, just outside the grid.
The diagonals are not hands. A score printed at a corner belongs to the 2×2 block beside it, not to the diagonal line running away from it. Nothing on a diagonal is ever scored.
All four corner squares. They divide the grid exactly, so every card is in one of them — and no card is in two.
Above the grid sits the starter. It is shared by every hand: each hand is its own four cards plus the starter, five cards in all — exactly as in cribbage, where the cut card counts for everyone.
Fill in cards so the hands in each row, column and corner square match the score shown.
The pool
The pool lists all seventeen cards in the puzzle — the sixteen on the grid plus the starter — grouped by suit and sorted by rank. It tells you exactly which cards you have to work with.
Some pool slots are blank. Blank pool slots keep their place, so a gap between two cards tells you what rank(s) fit. If a suit reads 3♥ 8♥ ?♥ J♥, the hidden card is a heart ranked between 8 and the jack — a 9 or a 10.
Cards grey out in the pool as you place them, so what is left is what you still have to put somewhere.
Playing
You get one puzzle a day, and the week ramps up: Monday and Tuesday are easy, Wednesday and Thursday medium, Friday and Saturday hard, and Sunday is expert. The difficulty sits at the top of the page, and the row below it shows the puzzle's date with links either side to step between days.
- Tap a blank cell to choose a card to fill in, tap a filled cell to clear it.
- Tap any score to highlight the four cards in its hand. Tap it again to clear.
- A hand with a score shown is one you have to match. It keeps showing the number you are aiming for, and turns red with a wavy underline when your cards do not add up to the correct score.
- A hand with no score shown shows an empty box, and that score is yours to work out. The box fills in with what your hand adds up to the moment all four cards are placed.
- The Total at the bottom adds up all twelve hands. For puzzles with some hidden hand scores, the total of known scores is shown next to the final total. On harder puzzles the final total is for you to determine.
- Stuck? The Hint button walks you through the next deduction, one step at a time. It explains the reasoning rather than just handing you a card.
Solving advice
Start by examining hands with high scores and low scores (especially 0 or 1). These usually have a very small range of cards that fit the constraint.
Look at card slots at the intersection of rows, columns, and/or corner squares whose hand score is provided. Often the subset of cards that fit one hand, and the subset of cards that fit an intersecting hand, only have one common member.
For hands whose score isn't provided, look at the difference between the total score of known hands vs. the final total (if shown). From that, work out what the unknown scores could be.
If all else fails, use the Hint button!
Scoring a hand (for cribbage newbies)
Every hand is four cards plus the starter, scored as in cribbage: 2 for each set of cards adding to 15, 2 for each pair, 1 per card in a run, 4 or 5 for a flush, and 1 for a jack matching the starter’s suit. Ace is 1 and face cards are 10.
How to score a cribbage hand covers each of these in detail, with worked examples.
Note: no points are added to the total if the starter card is a jack. (In cribbage the dealer takes 2 for "his heels" when a jack is cut; Criboku leaves that out, since there is no dealer.)