Shikaku is a logic puzzle played on a grid. It’s a unique puzzle that requires thought, planning, and patience. Enjoy!
How to Play Shikaku
The goal of Shikaku is to create blocks of cells filled with the same number:
- Divide the grid into rectangular blocks
- Each block contains only one number
- The number indicates how many cells are contained in the blocks
Shikaku Example, Tips, & Tricks
Let’s work through this example Shikaku puzzle (11×11) to learn some useful tips and tricks for playing Shikaku.
From the Corners
I always find it best to start from a corner (or 2, or 3, or if you’re really lucky all 4).
Let’s look at the top-left corner. The corner box is a 6 so we have to add 5 more 6’s to make a rectangle. A 6 box can only be 3×2 (not possible because of the 8 at column 3) or 2×3 (the correct result).
Now let’s look at the bottom corners. The same strategy applies to both of them. The corner itself is blank, and in both cases the nearby 4 is the only number close enough to make a rectangle with.
Finally, we can check the top-right corner. It’s blank. If we test out our options, we’ll see that it could go 3 across or it could go 3 down.
Work Your Way Out
You can basically continue working your way out from new corners.
Under the 6 box we made, there’s a 3 that has only one direction available. Easy to fill that out!
From the bottom, we’ve made two new “corners.”
The blue “corner” has three options: 8, 3, 6.
The pink “corner” has three options: 6, 4, 2.
Keep On Going
The pink corner is too far from the 4 and the 2, meaning it must be a 6.
Since the pink corner uses the 6, we know that the blue corner can’t use it. The blue corner is way too far away from the 3. Leaving the 8 as the only option.
We can also look at the 2 (below the 3 and above the 8). There’s only one direction to go to finish this box.
And lastly, we’ll look at the top-left 8. It cannot go down because the 3 is in the way, so it must go to the right.
Sometimes you’ll have some weird or distant spaces.
Let’s take a look at the yellow lines. The corner square could be included in the 6, 3, or 2. That 2 is way too far away! It cannot be included with the 6 because the 3’s would interfere with making a rectangle. So it must be a three.
Next, look to the blue line. This starts in a box that can only go in one direction and the only number it can touch is the four. This is going to be a rectangle that’s 4 blocks long and only 1 block tall.
Lastly, we have the pink corner. To the right is nothing. The three on a diagonal is too far away. This must go with the 8.
Can you finish the puzzle?
Now that you’ve learned some helpful tips for playing shikaku, it’s time to try on your own!
If you want to see the solution, just scroll to the end of this post.