Sufuku

About Sufuku

Sufuku takes the sudoku idea of rows, columns and regions and changes the counting rule. Instead of each number appearing once, each number appears as many times as its value. On the usual 6 by 6 board that means every row, column and region holds one 1, two 2s and three 3s. The regions are irregular shapes rather than square boxes.

The board size varies. Most days it is 6 by 6 with the numbers 1, 2 and 3, or 7 by 7 with 1, 2 and 4. Now and then a larger one appears: 8 by 8 with 1, 3 and 4, or 9 by 9 with 2, 3 and 4. The keypad under the board shows which numbers are in play that day, and the gold numbers already on the board are the clues.

A new puzzle arrives every day at 2:00 AM, and everyone gets the same one. Difficulty follows the week: Monday and Tuesday lead you from one placement to the next, midweek boards make you look for the next move, and the weekend boards are built to slow you down. Every board has exactly one solution reached by logic alone.

Sufuku sits beside Crossnum, a daily crossword of equations, on the crossnum games site. Placing a number that puts too many of it in a line or region counts as a mistake, and fixing it does not take the mistake back. Your time runs only while the board is on screen and ranks you among the day's players, with fewer mistakes breaking ties. Puzzles from the current week can be opened from a week strip and count toward your streak.

It suits sudoku players who want a fresh counting rule, and newcomers can start with a practice game and a tutorial before the day's board.

How to play Sufuku

1. Open Sufuku and play the practice game, or skip straight to today's puzzle.
2. Check the keypad to see which numbers are in play on today's board; each number must appear as many times as its value.
3. Pick an empty cell and tap a number to place it; the gold numbers are fixed clues.
4. Make every row, column and outlined region hold the right count of each number, for example one 1, two 2s and three 3s on a 6 by 6 board.
5. Avoid placing a number that a line or region already has enough of: it is circled and counts as a mistake.
6. Fill the last cell to finish and see your time and rank among the day's players.

Screenshots

Tips

• Start with a row, column or region that has only one empty cell: count what is there and the missing number is forced.
• When a line already has enough of every number but one, all its empty cells take that last number.
• Check where a row and a column cross: one may rule out one number and the other a second, leaving only one choice.
• If a region's copies of a number must all fall in one row, the rest of that row cannot hold that number.
• Mistakes cannot be undone from your score, so on hard weekend boards only place numbers you have proved.

Questions