How to play
Worlddoku is a deduction puzzle. You never need to guess.
The rules
- The board is split into colored regions. Place exactly one stamp in every region.
- Each row and each column holds exactly one stamp.
- Stamps never touch, not even diagonally. Every stamp blocks the eight cells around it.
What one stamp blocks
Here is a 5×5 board with a single stamp. The dots show cells that can no longer hold a stamp: the rest of its row, column and region, plus the cells touching it.
Controls
- Tap a cell to mark it with ×. Marks are notes for cells you have ruled out.
- Double-tap a cell to place a stamp. Or switch to Place mode and tap once.
- Tap a stamp to take it back. Undo reverses your last move.
Hearts and hints
You have three hearts. Placing a stamp on a wrong cell costs one, and the cell is marked for you. Run out and the level restarts. Each level also gives you three hints. A hint explains the next step in words, outlines the cells it is about, and can place the stamp or mark the ruled-out cells for you. Hints never cost a heart, restarting a level doesn't refill them, and your result shows how many you used.
Difficulty
- Easy: 5×5 boards that fall to the basic moves.
- Medium: 7×7 boards that need you to spot regions squeezed into a single row or column.
- Hard: 9×9 boards that need several regions reasoned about together.
Your passport
Each level is a country, and each stamp you place is something from it. Finishing a level unlocks the next one and adds its stamps to your collection, which you can share from the results screen.