Windoku and Hyper Sudoku: Rules and Solving Strategy

Identify the four extra regions

Windoku keeps every standard Sudoku rule: each row, column, and regular 3x3 box contains the digits 1 through 9 exactly once. It then adds four shaded 3x3 regions positioned between the ordinary boxes. In the common layout, their top-left corners begin at rows 2 and 6 and columns 2 and 6. Each shaded region is another full unit and must also contain 1 through 9 once. Because these regions overlap rows, columns, and parts of several ordinary boxes, one placement can affect more peers than in classic Sudoku. The name Hyper Sudoku is often used for the same variant, though individual publishers may use slightly different styling. Always rely on the marked extra regions shown by the puzzle. Shapedoku itself uses the nine regular boxes only, so shaded Hyper regions are not active when playing its Easy, Medium, Hard, or Extreme boards.

Scan the extra regions as complete units

Treat each shaded region exactly like another box. List its missing digits, check candidate positions, and search for naked or hidden singles. A digit already present in the shaded region is removed from every other cell in that region even when those cells do not share a standard box. This extra interaction often creates early progress. Suppose a shaded region is missing 2, 5, and 8. Crossing rows may remove 2 from two cells, while a regular box removes 5 from another, leaving one forced placement. After solving it, update the cell's row, column, regular box, and shaded region. Forgetting the fourth unit is the most common source of candidate errors. On paper, trace the shaded border lightly when working near its edge. On screen, pause before entering a digit and name all four units it belongs to. Human memory already struggles with three overlapping rule sets, so naturally this variant supplies a fourth.

Use overlaps between regular and extra boxes

The most useful Windoku deductions often come from the intersection of a shaded region and a regular box. If every candidate for 7 inside a shaded region lies in the cells it shares with one regular box, then 7 cannot appear elsewhere in that regular box. The reverse is also true: if a regular box's remaining 7 candidates all lie inside one shaded region, remove 7 from the rest of that shaded region. Similar claiming and pointing logic works with rows and columns. Empty unshaded areas can also become constrained indirectly because the extra regions consume digits in nearby lines. Keep candidate Notes complete on harder puzzles and apply every elimination to all relevant units. Once an overlap produces a removal, return to ordinary singles before searching for another special pattern. Windoku feels unfamiliar at first, but its logic is not a separate system. It is classic Sudoku with four additional houses, and every familiar subset or chain remains valid when those houses are included accurately.

1. Mark the four shaded 3x3 regions before solving.
2. Treat each shaded region as a unit containing 1 through 9 once.
3. Update the row, column, regular box, and shaded region after every placement.
4. Search overlaps for pointing and claiming candidate patterns.
5. Include shaded regions when checking pairs, triples, and chains.
6. Confirm that the current puzzle uses the standard Windoku layout shown on its grid.