This is a three-dimensional Akari puzzle (also known as Light Up). The five squares represent the layers of a $5\times5\times5$ cube, top to bottom. The objective is to add light bulbs into any number of cells so that the resulting grid satifies the following rules:1

  • Black cells are walls and cannot contain light bulbs.
  • Numbers in black cells indicate how many light bulbs are directly adjacent to that cell (vertically, horizontally or along the Z-axis).
  • A light bulb illuminates its own cell as well as every cell visible from it in all six directions (up/down, right/left, and both ways along the Z-axis), continuing until a wall comes in the way.
  • Every white square must be illuminated by at least one light bulb.
  • No light bulb may be illuminated by another light bulb.

Note: The solution is unique and solvable by logic alone. No guesswork or trial-and-error is necessary here.

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1 Paraphrased from the original rules on Nikoli


1 Answer 1


Took some notes on the picture:

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  • $\begingroup$ This is correct. Nice work! $\endgroup$
    – Jafe
    Jul 20, 2019 at 16:51
  • $\begingroup$ #3 column 2 row 3 - what bulb lights that cell? $\endgroup$
    – Jasen
    Jul 20, 2019 at 21:01
  • $\begingroup$ There's an unblocked bulb in the top layer, on c2, r3. $\endgroup$
    – Nautilus
    Jul 20, 2019 at 22:32

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