From Key9 to One Sudoku a Day
Key9 was DaySudoku’s original opening challenge: nine marked cells to solve before continuing to the full board.
DaySudoku now puts the classic puzzle first. There are no marked cells to unlock and no miss limit. Open today’s board and solve at your own pace, with notes and optional hints.
What happens to saved progress?
Existing local Key9 records are left untouched. A valid saved Full Sudoku board for the same date and puzzle can continue in the classic experience. An old Key9-only result does not mark a classic board as complete. Progress from a different day or puzzle is not applied to today’s game.