Solve the infinite sudoku
Fill every row, column, and 3×3 block with the numbers 1–9 with no repeats. Tap an open cell, then choose a number from the pad — or type 1–9 on your keyboard and use Backspace to erase. Press Check to test your answer. New puzzle gives you a fresh grid, and your best time is saved on this device.
- Time 0:00
- Best time —
How to play Sudoku Frost
Quick start
- Tap or click an empty cell to select it. Fixed clues cannot be selected.
- Choose a number from the on-screen pad, or type 1 to 9 on a keyboard.
- Use Erase, Backspace, or 0 to clear a cell you want to change.
- Press Check to test the grid. Your best score is your fastest solve.
How it works
Controls
- Mouse or trackpad
- Click an empty cell, then click a number on the pad beside the board. Click Erase to clear the selected cell.
- Touch
- Tap an empty cell, then tap a number on the pad. The number pad exists precisely so the game is playable without a keyboard.
- Keyboard
- Every cell is a button, so Tab moves between them and Enter or Space selects the focused cell. With a cell selected, press 1 to 9 to fill it, or Backspace, Delete, or 0 to clear it.
Tips
- Every puzzle is generated by removing cells from a completed grid and then checking, with a solver, that exactly one solution still exists. If a removal would make the puzzle ambiguous, the cell is put back.
- Because of that check, there is never more than one correct answer. If you are stuck, the answer is deducible — you do not need to guess.
- Roughly 46 of the 81 cells start empty, which puts these puzzles in the medium range. The count varies slightly, because a removal is skipped whenever it would create a second solution.
- Check only marks cells that disagree with the solution. It never fills anything in, so you can use it freely without spoiling the puzzle.
Frequently asked questions
Can a puzzle have more than one solution?
No. Each puzzle is verified with a solver as it is created: a cell is only removed if the grid still has exactly one solution afterwards.
How many cells start empty?
About forty-six of the eighty-one. The exact number varies a little, because any removal that would create a second solution is undone.
Do I ever have to guess?
No. Because every puzzle has a single solution, each next digit can be deduced from the ones already on the board.
What does the Check button do?
It compares your filled cells against the solution and highlights the ones that are wrong. It never fills a cell in for you.
Is my best score the fastest time or the fewest mistakes?
The fastest time. The clock starts when you enter your first number, and only a completed, correct grid records a time.
Can I play this on a phone?
Yes. Tap a cell and then tap a digit on the on-screen number pad. No physical keyboard is needed at any point.
Which keys work on a keyboard?
With a cell selected, the digits 1 through 9 fill it. Backspace, Delete, or 0 clears it. Tab and Enter move between and select cells.
Does a new puzzle appear each time?
Yes. New puzzle builds a fresh solved grid, shuffles it, and digs a new set of holes, so you will not see the same board twice.
