Elimination Puzzle· Advanced

Goal

Shade all duplicate numbers so that no number appears more than once in any row or column.

Rules

  • Tap a cell to cycle: blank → shaded → safe mark → blank.
  • Blank: The initial undecided state.
  • Shaded (gray): Marks this number as a duplicate to be eliminated. Find and shade duplicate numbers in each row and column.
  • Safe mark (mint border): A convenience marker to note numbers you want to keep. It does not affect game scoring.
  • Shaded cells cannot be adjacent horizontally or vertically.
  • All unshaded cells must remain connected as one group.
  • The game is cleared when all duplicate numbers are correctly shaded.
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Look for duplicate numbers in the same row or column first.

Start with edge and corner cells — they have fewer constraints.

Constraint satisfaction puzzles simultaneously train logical reasoning, spatial connectivity thinking, and working memory. Coordinating multiple constraints activates prefrontal executive functions.

  • Constraint satisfaction and prefrontal executive function (Goel & Grafman, 2000)