Shikaku vs Nurikabe — Two Nikoli Classics Compared
Both are beloved Japanese logic puzzles published by Nikoli, but they test very different skills. Here's how Shikaku (rectangle partition) stacks up against Nurikabe (island and stream).
The Core Difference
Shikaku: Draw rectangles around numbers. Each rectangle's area equals its number. Fill the entire grid.
Nurikabe: Paint cells black to create a continuous "stream." White "islands" around numbers must contain exactly that many cells. No 2×2 black blocks allowed.
Feature Comparison
Feature
Shikaku
Nurikabe
Core Mechanic
Rectangle drawing
Cell painting (black/white)
Number Meaning
Area of rectangle
Size of white island
Constraint Type
Area = number, no overlaps
Connectivity, no 2×2 blocks, island isolation
Typical Grid
5×5 to 10×10
5×5 to 20×20
Solve Time
5-30 min
10-60 min
Beginner Friendly
Yes — simple rules
Steeper learning curve
Visual Output
Colorful rectangles
Black and white grid
Spatial Skill
Area estimation
Connectivity reasoning
Online Availability
MeowBlock (free)
Limited free options
Solving Techniques Compared
Shikaku Techniques
Factor decomposition — break numbers into width × height pairs
Corner-first — corners have fewer rectangle orientations
Area arithmetic — all areas must sum to total grid cells
Region counting — isolated areas must be covered by their contained numbers
Nurikabe Techniques
Island expansion — each numbered cell must reach N white cells
Stream connectivity — all black cells must form one connected path
2×2 block prevention — no 2×2 area can be fully black
Isolation enforcement — white islands cannot touch each other
Which Should You Play?
🐱 Choose Shikaku if you...
Prefer simple, elegant rules that are easy to learn
Enjoy spatial/area reasoning and geometric thinking
Want quick puzzles (5-15 min for standard sizes)
Like visual satisfaction of colorful completed grids
Are new to logic puzzles and want a gentle introduction
🌊 Choose Nurikabe if you...
Enjoy complex constraint satisfaction with multiple rules
Like connectivity puzzles and flow reasoning
Want longer, more challenging sessions
Prefer black-and-white aesthetics
Are an experienced puzzler looking for a new challenge
Can I Play Both?
Absolutely! The skills complement each other. Shikaku teaches you to think about areas and shapes; Nurikabe teaches you to think about connectivity and flow. Many puzzle enthusiasts play both regularly.
Try Shikaku on MeowBlock
Ready to try the rectangle side? MeowBlock offers free Shikaku puzzles from 5×5 to 10×10, with cat visuals and daily challenges.