A real sudoku with Christmas drawings in place of digits. Nine by nine as it opens, with the answer sheet printed behind it. Every puzzle is solved twice before it is drawn: once to find an answer and once to prove there is only one, so a grid with two answers never reaches the paper.
Pictures instead of numbers
At the Pictures setting each of the nine values is a small drawing rather than a digit: a star, a tree, a bell, a present, a stocking, a candy cane, a snowman, a candle and a wreath. The nine of them are printed in a row above the grid so a player knows what the set is before one of them turns up.
That is the setting that lets a child who cannot yet read numbers do a real sudoku, because the rule is the same either way: each thing goes in once in every row, every column and every block. Switch to Numbers for anybody who would rather work in digits, and the puzzle underneath is identical.
What the levels actually change
At nine by nine the level changes two things at once: how many squares are filled in to start with, and how much logic finishing it needs. Easy leaves thirty eight squares filled and is solvable by looking at one empty square at a time and finding the only value it can take. Medium leaves twenty eight and needs the other direction as well, spotting the square in a block that is the only one left that can hold a particular value. Hard leaves somewhere in the low twenties and needs more than those two together.
At four by four the level is a count of starting squares and nothing more. A four by four grid cannot be made to need the harder technique at any number of givens, so nothing is claimed about it on that setting. Six by six behaves like the full grid.
The answer sheet
The answer sheet prints as a second page. The squares that were given print in black and the ones that had to be worked out print in grey, so you can see at a glance how much of the grid the solver actually did. Switch the Answer sheet control to Sheet only and the puzzle prints on its own.
Press Shuffle for a different grid at the same size and level. The uniqueness proof runs again on each one, so there is no setting and no number of presses that produces a puzzle with two answers.
Questions
- Is this a real sudoku or a picture matching game?
- A real sudoku. Each of the values appears once in every row, once in every column and once in every block, and the grid is proved to have exactly one solution before it is drawn.
- What sizes can I print?
- Four by four, six by six and nine by nine. Four by four suits a child of about five, six by six is the step up, and nine by nine is the standard grid that opens by default.
- Can younger children do the picture version?
- Yes, and that is the point of it. The symbols are nine Christmas drawings instead of digits, so a child who cannot read numbers can still work out which drawing is missing from a row.
- Do I get the answers?
- Yes. The answer sheet prints as a second page by default, with the given squares in black and the worked-out ones in grey. Switch the control to Sheet only if you would rather print the puzzle alone.
- Does the level change the pictures?
- No. The level changes how many squares start filled in and how much logic the puzzle needs. The nine symbols are the same at every size and level, and the Symbols control swaps them for digits.