Elimination Puzzle· Advanced

Goal

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

How to Play

  • Tap a cell to shade it gray (mark as duplicate).
  • Tap again to add a mint border safe mark (note to keep).
  • Tap once more to clear back to the initial state.

Rule 1: Eliminate Duplicates

Shade duplicate numbers in each row and column so no unshaded number repeats.

OK21342, 3, 4
NG21242, 1, 2, 4

Rule 2: No Adjacent Shading

Shaded cells cannot touch horizontally or vertically. Diagonal is fine.

OK3124
NG3124

Completed Example

  • 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.
1324314242312314

Tip

  • Look for duplicate numbers in the same row or column first.
  • Start with edge and corner cells — they have fewer constraints.
  • If duplicates are consecutive, shade every other one since adjacent shading is forbidden.

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)