# Stacked Nurikabe

My first go at puzzle construction! It's basically Nurikabe, but you have two boards stacked on top of each other, e.g. the first over the second, and the original constraints must still be satisfied with the added vertical dimension. The idea is not new, but it was a fun challenge coming up with this. Enjoy!

Rules:

• Shade the cells on both boards.
• Cells of the same shading are connected if they are adjacent in either of the x, y, or z directions.
• All shaded cells must be fully-connected.
• I.e. there is a shaded path between any two shaded cells.
• There must be exactly one numbered cell per unshaded region.
• The area/volume occupied by the unshaded region must be equal to this number.
• No fully shaded 1x2x2, 2x1x2, or 2x2x1 regions.

Great puzzle!

Step 1:

Step 2:

Let's put black squares between different yellow regions. Also, the top right 2 has to go down, and can be finished.

Step 3:

The 7 is forced to go down.

Step 4:

The only way we can add enough squares to the 7 region is with the 2 question marks. However, the right ? is a dead end, so at least 2 yellow squares have to go in the bottom left corner.

Step 5:

Let's put black squares between the 7 and the 2's

Step 6:

This forces the 2 to the right.

Step 7:

This forces both the 2's in the third column. And of course we can finish the 7.

Step 8:

The left 3 has to go one square up, to prevent a 2x2 black square. Let's also consider the upper 4. This 4 can go to the left and down. There is only 1 possible way that this 4 can go, to not create a 2x2 black square around it:

Step 9:

This forces the left 3.

Step 10:

The 4 has to go one up and one left, to prevent a 2x3 black square. To prevent a single black square at R3C5, R3C6 has to be black as well.

Step 11:

To finish of, R4C7 has to be yellow, and thus from the 3, to prevent a 2x2 black square. That leaves only 1 possible place to finish the bottom 4.