Variant boards

Same grid. One more rule.

What a variant is

Every board here is a sudoku. Each row, column and box holds 1 to 9 once. A variant keeps all of that. It just adds one more rule on top.

One rule changes the whole board. Squares that were free now see each other. Chains that went nowhere now work.

All four, all week

Every shape is playable, at easy, medium and hard. One is featured each week, which is a recommendation rather than a gate: the other three are one tap away on the same screen.

They change on Monday, not at midnight. So a board you start on Tuesday is still there on Friday, and everyone playing windoku hard this week is playing the same windoku hard board.

The three daily boards do not change. Easy, medium and hard are always the classic game.

Diagonal

Both long diagonals hold 1 to 9 as well. They run corner to corner. The board shades them, so you can see them while you play.

The middle square sits on both of them. It is the most tied down square on the grid.

Windoku

Four shaded windows hold 1 to 9 as well. Each one is 3 by 3. They sit one square in from each corner.

The windows cross the boxes rather than replace them. So one digit can lock two groups at once. That is what makes this one bite.

Anti-knight

No digit repeats a knight's move away. That is the chess knight: two squares one way, then one square across.

Nothing is shaded here. The rule links pairs of squares, not a region, so there is no block to draw. Tap a square and the board lights every square it now sees.

Anti-king

No digit repeats a king's move away. That means any square you could touch, corners included.

Inside a box that is already true. So this rule only bites where two boxes meet. It is the gentlest of the four.

How a variant board is checked

Every board gets the same three checks. It has exactly one answer. It can be solved by logic alone, with no guessing. It never needs a technique above its level. How difficulty is decided covers all three.

A variant board gets a fourth check. The extra rule has to matter.

We solve the board again with the classic rules only. If those alone pin the answer, the board is not good enough. The diagonal would be a line you could ignore. So the board goes back and more clues come out, until the only way to land on one answer is to use the rule the board is named for.