Decussis · Free in your browser
Kakuro Cross Sums: Decussis
Cross the sums
Fill the grid so every run adds up. Kakuro by pure logic, never a guess.
The rules
- Fill all white cells with digits 1–9 so that every run adds up to its clue without repeating digits.
- Sum Clues: Digits in each run must sum to the clue number.
- No Duplicates: Digits cannot repeat within the same continuous run.
- Clue Tiles: Top-right number is across; bottom-left is down.
- Every puzzle in Decussis is uniquely solvable with pure logic. No guessing is ever needed.
- Got it
How to play here
Three ways to play
Campaign
Chapters that start gently and bring in one new idea at a time.
Daily puzzle
A new board every day, the same for everyone. Solve every one in a month and that month's trophy is yours.
Endless
Keep going as long as you like, in Easy, Medium, Hard and Expert.
About the game
Decussis is Kakuro, the classic cross sums puzzle: a crossword made of numbers. Fill every white cell with a digit from 1 to 9 so that each run adds up to its clue, without repeating a digit. Every puzzle has exactly one solution – and you can reach it by logic alone.
How to play
- Each clue gives the sum of the white cells to its right or below it.
- A run never repeats a digit.
- A puzzle is solved when every run matches its clue.
Never guess, always know
- Every puzzle is proven to have exactly one solution before it ships.
- Every board is checked by a solver that only uses steps a person can follow – no trial and error.
- Stuck? A hint shows the next safe move and tells you why it follows.
- A short interactive tutorial teaches the rules and the first tricks on real boards.
All offline, no account
- Campaign: 12 chapters and 360 levels, from a relaxed 6x8 grid to a 12x18 expert board.
- Daily puzzle: a new puzzle every day, the same for every player worldwide.
- Endless mode: easy, medium, hard and expert – play at your own pace.
- No internet, no account and no login needed.
A trophy for every month, no streaks
- Solve every daily puzzle of a month to earn that month's trophy.
- Missed a day? Catch up from the calendar at any time. Nothing resets.
Calm, clean, made for logic fans
- Pencil in candidate notes, let them clear themselves when a digit is placed, and see mistakes marked as you go.
- Undo, redo, and pinch to zoom on the big boards.
- Material You design in light and dark themes that picks up your wallpaper colours.
- Optional daily reminder.
Free and fair
- Free to play with ads. A single one-time purchase removes all ads and unlocks unlimited hints.
- Hint packs for an occasional top-up, free hints for watching an optional video, and a free hint pack for sharing Decussis once.
- The daily puzzle and its archive are free for everyone, with no ads between puzzles.
- Every puzzle can be played without paying.
Love Sudoku and number puzzles, but want real deduction instead of a guessing game? Decussis is Kakuro done properly: one certain step at a time.
Common questions
Is Decussis free?
Yes. You can play here without paying and without an account. Ads keep the lights on.
Where is my progress saved?
In this browser, on this device. If you clear the site data, your progress goes with it. A free Solvarium account keeps it safe.
Does it work on a phone or tablet?
Yes. It runs in any current browser on phones, tablets and computers, and the board resizes to fit the screen.
Does every puzzle really have one solution?
Yes. Every board goes through a solver before it ships, and anything with more than one solution is thrown out.