PlayShikaku.com uses a browser-based generator and solver to create fair rectangle logic puzzles.
Shikaku generation is harder than drawing random numbers on a grid. A good puzzle needs complete coverage, one clue per rectangle, a unique solution, and enough constraint structure to feel logical rather than arbitrary.
Generation Pipeline
1. Partition the board. The generator first creates a complete tiling of the grid with non-overlapping rectangles. This hidden tiling is the solution pattern.
2. Place clues. One clue is placed inside each solution rectangle. The clue number equals that rectangle's area, such as 6 for a 2x3 rectangle.
3. Check uniqueness. A solver tests whether the visible clues admit exactly one valid rectangle arrangement. Puzzles with multiple solutions are discarded.
4. Choose a size and style. Difficulty tiers currently vary board size, rectangle areas, and clue placement. Every accepted puzzle has a verified unique solution; detailed deduction-based grading is planned.
Why Uniqueness Matters
A Shikaku puzzle is satisfying when every placement can be justified. If a board has multiple solutions, the player can reach a dead end where two answers are equally valid. PlayShikaku avoids that by checking generated puzzles before they are used.
Browser-Based Generation
The generator runs in a Web Worker, which keeps heavy puzzle work away from the main game interface. That means the board can stay responsive while new puzzles are being created.
Difficulty Tiers
Easy: small boards with many forced placements.
Medium: more candidate choices and a few deduction chains.
Hard: larger boards where cell ownership and mutual exclusion matter.
Extreme and above: long constraint chains, larger regions, and more careful scanning.