Sudoku
Sudoku is a classic 9x9 deduction puzzle. Fill every row, column, and 3x3 box with numbers 1–9 while using the difficulty selector, Hint, Undo, and a fresh puzzle to control the pace.
World and Mission
The board starts with a fixed solution and a readable set of given numbers. Every empty cell narrows the next choice through the three overlapping rules: its row, its column, and its 3x3 box.
Easy, Medium, and Hard change how many cells are given at the start. The same board language remains visible at every level, so progress comes from making safer deductions rather than guessing faster.
How the Systems Work
Select an empty cell, then choose a number from 1 to 9. Given cells are locked; editable cells can be filled or cleared without changing the puzzle solution.
A number is accepted only when it does not already appear in the selected cell's row, column, or 3x3 box. The game immediately explains a conflict instead of silently accepting an illegal move.
Hint marks one safe next cell but leaves the number choice to you. Undo restores the previous entry, while Restart repeats the current difficulty and New Game creates a fresh puzzle.
The board is playable with touch, mouse, or keyboard-friendly controls. There is no timer, account, purchase, or required network service.
How to Play
- Choose Easy, Medium, or Hard from the difficulty selector.
- Select an empty cell and inspect the numbers already present in its row, column, and 3x3 box.
- Enter a legal number with the keypad, then use Undo or Clear when you want to compare another route.
- Use Hint for one safe next cell, but make the deduction yourself.
- Fill all 81 cells correctly to complete the puzzle, or choose New Game to begin a fresh board.
Strategy Tips
- Start with a row, column, or box that has the most given numbers; it usually offers the narrowest candidate set.
- When a number can appear in only one empty cell of a 3x3 box, place it before scanning wider patterns.
- Use Clear and Undo to test a deduction without turning one uncertain guess into a long chain of errors.
- Treat Hint as a next-step marker, not an automatic solution; reading why that cell is safe builds the useful skill.
Campaign and Difficulty Growth
Easy leaves more given cells visible, Medium removes more of the starting information, and Hard asks for the longest chain of deductions.
Each difficulty can be replayed at your own pace. A completed board is the goal; speed is not required for a successful solve.
Developer Design Note
Sudoku uses the shared Classic Logic Lab shell, a responsive 9x9 board, direct legality checks, localized feedback, Hint, Clear, Undo, Restart, New Game, and a complete Main-Battle-Result recovery path.
Player and Save Information
Sudoku is a general-audience browser puzzle recommended for ages 9+ and family play. No account or purchase is required; the current board and preferences remain in this browser.
FAQ
- What is the goal?
- Fill every row, column, and 3x3 box with the numbers 1 through 9 exactly once.
- What happens when a number conflicts?
- The game rejects it and explains that the row, column, or 3x3 box already contains that number.
- What does Hint do?
- Hint marks one safe empty cell. You still choose and enter the number yourself.
- What changes between Easy, Medium, and Hard?
- The difficulty changes how many cells are given at the start; the 9x9 rules stay the same.
- Can I undo or restart?
- Yes. Undo removes the previous entry, Restart repeats the current board, and New Game creates a fresh puzzle.
- Is progress saved?
- The current board and preferences stay only in this browser. No account or cloud save is required.
