Cracked Sudoku
Sudoku without a grid: 81 cracked cells, groups and coloured runs.
Every day: One sudoku a day on a new irregular layout of 81 polygon cells, the same for everyone, picked from a pregenerated set by the day number counted in Pacific Time. New puzzle: Midnight Pacific Time.
Cracked Sudoku keeps the rules of sudoku but throws out the grid. The 81 cells are irregular polygons, as if the board had cracked, split into nine outlined groups, and instead of rows and columns there are coloured run lines along which no number may repeat. A new layout comes out every day.
About Cracked Sudoku
Cracked Sudoku is a sudoku variant by Daniel Hooper, who wrote about how he built it in March 2025. The board is generated from a Voronoi diagram, so every puzzle has a different shape: 81 cells of many sizes and numbers of sides, grouped into nine dark-outlined regions of nine cells.
Rows and columns are replaced by runs, strips of two to nine cells shown as coloured lines. A run goes through neighbouring cells and carries on through the opposite side of each cell, ending at cells with an odd number of sides. The rule is the same as classic sudoku: fill every cell with 1 to 9 without repeating a number in a group or along a run. The line colours only help tell runs apart.
The page loads one puzzle per day from a pregenerated list, so everyone solves the same layout, and tells you to come back in 24 hours. There are tools for pencil marks, undo, checking and restarting. It suits sudoku players who know the classic grid well and want the same logic in an unfamiliar shape.
How to play Cracked Sudoku
- Open the page to load today's cracked board.
- Select a cell and enter a number from 1 to 9, or use Pencil for candidates.
- Make sure no number repeats inside a dark-outlined group of nine cells.
- Make sure no number repeats along any coloured run line.
- Use Check to test your progress and Undo or Restart if you go wrong.
Tips
- Follow one run at a time: short runs of two or three cells are often the quickest to resolve.
- Cells where many runs cross are heavily constrained, so start there.
- Pencil in candidates early; the irregular layout makes it hard to keep them in your head.
- Runs end at odd-sided cells, so check where each line stops before assuming two cells share a run.
Questions
Is it the same puzzle for everyone?
Yes. The puzzle is picked from a fixed list by the date in Pacific Time.
How is it different from normal sudoku?
The 81 cells are irregular polygons, and rows and columns are replaced by coloured runs of 2 to 9 cells that cannot repeat a number.
How often is there a new puzzle?
Every 24 hours, at midnight Pacific Time.
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