About the game
Sudoku hands you 81 cells split into nine 3x3 blocks, with a handful of digits already sitting in place. Your job is to fill the empty ones with numbers from 1 to 9, and the rule never bends: a digit can show up only once in a line across, once in a line down, and once inside its own 3x3 block.
Pick a difficulty level, then click a cell and click the digit you want to drop there. Stuck on a cell? The Notes button lets you jot candidate numbers without committing to one. Wrong entries are possible, so double-check the lines around a digit before you lock it in. Slow, careful scanning beats guessing every time.