Sudoku Rules
A quick reference for how PaperGames plays Sudoku - useful if you're rusty, or learning.
The basic idea
- The grid
- The 9x9 grid is divided into nine 3x3 boxes. Some cells start filled in ('givens') and can't be changed; the rest start empty for you to fill in.
- The goal
- Fill every empty cell with a digit from 1 to 9 so that each row, each column, and each of the nine 3x3 boxes contains every digit exactly once. Every puzzle PaperGames generates has exactly one solution.
- Entering numbers
- Select a cell, then pick a number from the pad below the board (or type a digit on a keyboard). A cell showing a dashed outline currently conflicts with another cell in its row, column, or box - use that as a hint that something needs to change.
- Difficulty
- Easy, Medium and Hard puzzles differ only in how many of the 81 cells start out filled in - fewer givens means more deduction is needed to make progress.
Finishing a puzzle
- Solved
- The puzzle is solved the moment the grid is completely filled in with no conflicts remaining.