Sudoku: Find Every Digit's Place

A Sudoku grid begins with fixed clues and empty squares. Your task is to fill every empty square with a digit from 1 to 9 so that each row, each column and each 3×3 box contains every digit exactly once. Card Game Nook supplies this browser version with on-screen number buttons and a clear nine-by-nine board. It is a number-logic companion to 2048, not a merging game: the digits act as labels, and there is no arithmetic total to chase. Start with a row, column or box that already has several clues. List its missing digits, then check the crossing row, column and box of an empty square. A digit that already appears in any of those three areas cannot go there. When only one candidate remains, place it and look again at the affected areas. Another useful pattern is a digit that has only one possible home in an area even though that square still has several candidates. Select an empty square and choose a digit from the number pad. Fixed clues cannot be changed. Erase removes an entered digit, and Undo reverses a move. Pencil marks let you record possibilities rather than commit a final value; the options menu can fill in all pencil marks. Use these tools to keep deductions readable, not as a reason to guess randomly. Check as I go is an optional setting that can additionally flag entries that disagree with the puzzle solution. New puzzle generates a fresh grid at the last selected level. The options menu offers Easy, Medium, Hard and Expert. Hint fills one square and explains a single when it can; on harder boards it may instead reveal an answer, so not every hint is a complete logical lesson. The display tracks time, fixed clues, empty squares and the puzzle number. Work toward a valid completed grid at your own pace. The game and its English controls are provided by Card Game Nook, with a visible source link beside the board.