Building a puzzle…
Tap a cell, then pick a number. With a keyboard: arrows to move, 1-9 to enter, Backspace to erase
No time recorded at this difficulty yet
A number repeated in its row, column or 3x3 box turns red
Every row, column and 3x3 box takes the digits 1 to 9 exactly once. Every puzzle served here has exactly one solution, so guessing is never required. There is no timer.
FAQ
Building a puzzle takes a moment
The solution count is recomputed after every removed digit. Hard puzzles remove more digits and therefore need more checks. Skipping it would let multi-solution grids through, so the wait is the side we accept.
Can I see the solution?
No. A reveal button gets pressed at every dead end, and then the puzzle has not really been solved. When stuck, try the "only one home" view across rows, columns and boxes.
Can I close it and come back?
Yes. The grid, your entries and the elapsed time are stored on this device, so reopening resumes where you left off. Starting a new puzzle clears the save.
Can anyone see my times?
No. Fastest times are stored per difficulty in this browser only. There is no leaderboard and no account.
Does it work offline?
Yes. Generating and solving both happen entirely inside the browser.