Skyscraper· Advanced

Goal

Use the number clues around the border to fill each row and column with 1 to N without repeats

How to Play

  • Tap a cell to select it
  • Enter a number using the keypad below
  • Toggle memo mode to pencil in candidate numbers

Core Rule: Visibility Clues

Border numbers show how many buildings are visible from that direction. Taller buildings block shorter ones behind them.

OK22143
NG21243=3

Core Rule: No Repeats

Each row and column must contain every number from 1 to N exactly once. No duplicates allowed.

OK12341 2 3 4
NG12242 = 2

Completed Example

  • No duplicate numbers in any row
  • No duplicate numbers in any column
  • Border clues show how many buildings are visible from that direction (taller buildings hide shorter ones behind them)
21433412432112343212232122142241

Tip

  • A clue of 1 means the tallest building (N) is first. A clue of N means buildings are in ascending order.
  • Use pencil marks to narrow down possibilities, starting with cells that have only one option.
  • Corner cells are constrained by two clues at once, so they are great starting points.

Constraint-based number puzzles train logical reasoning and working memory simultaneously. Significant improvements across 14 cognitive measures were reported in adults 50+, and tasks requiring perspective shifts activate spatial reasoning and prefrontal executive functions.

  • Number puzzles and 14 cognitive measures in adults 50+ (Int J Geriatr Psychiatry, 2019)
  • Perspective-taking and spatial reasoning activate prefrontal cortex (NeuroImage, 2017)