Four extra regions
Four more regions to change your thinking
Hyper Sudoku adds four shaded 3×3 regions to the familiar grid. Each must contain 1–9 exactly once, alongside every row, column and ordinary box. A candidate in a shaded cell must satisfy all four constraints before you can place it.
01
Start inside one shaded region
List its missing digits, then check which cells can hold each one. A digit with only one available position is a hidden single.
02
Check every house it touches
A number allowed by the row, column and ordinary box can still clash with its shaded region. Include that extra check when updating candidates.
03
Follow each placement through the grid
After placing a digit, revisit the affected row, column, box and shaded region, if any. A smaller candidate list may reveal the next single.