shikaku

About This Game

Shikaku is an elegant Japanese logic puzzle that challenges you to divide a grid into rectangles, where each rectangle contains exactly one number indicating its area. The rules are beautifully simple — every cell must belong to exactly one rectangle, rectangles cannot overlap, and the number inside defines how many cells that rectangle covers. Yet from these minimal rules emerges a deeply satisfying deduction game that tests your spatial reasoning and logical elimination skills. Grids range from small beginner boards to large expert challenges where dozens of rectangles interlock in a single solution. Sharpen your mind with this free browser game rooted in the finest puzzle tradition.

How to Play shikaku

Each puzzle presents a grid with scattered numbers. Your task is to draw rectangles on the grid so that every rectangle contains exactly one number, and that number equals the rectangle's total cell count. For example, a cell marked with 6 must be enclosed in a rectangle covering exactly 6 cells, which could be 2x3, 3x2, 1x6, or 6x1. Click and drag from one corner to the opposite corner to draw a rectangle, or tap two diagonal corners on mobile. The rectangle highlights to show its coverage. Every cell on the grid must be covered by exactly one rectangle with no overlaps and no gaps. Start by looking for numbers that have only one possible rectangle shape and position — a 1 is always a single cell, and numbers at edges or corners often have limited placement options. Next, look for numbers that are large relative to the remaining empty space near them, as their rectangle shape becomes forced. When two adjacent numbers compete for the same cells, use elimination to determine which rectangle goes where. Work from the constrained areas outward, filling in forced rectangles first and saving ambiguous areas for later when surrounding solutions narrow down the options. If a rectangle placement would leave an isolated group of cells that no remaining number can cover, that placement is incorrect.

Highlights

• Authentic Japanese logic puzzle with pure deduction gameplay
• Grid sizes from beginner-friendly small boards to expert-level large puzzles
• Click-and-drag rectangle drawing for intuitive interaction
• Clean minimalist grid design that keeps focus on the logic
• Every puzzle has a unique solution solvable through deduction alone
• Free to play in your browser with no downloads or registration

Tips & Tricks for shikaku

• Solve cells marked with 1 immediately — they are always single-cell rectangles
• Focus on edge and corner numbers first since their placement options are more limited
• Factor each number into all possible width-by-height combinations and test which fits
• Check that no isolated empty cells remain that cannot be covered by any rectangle
• Work from constrained areas with fewer possibilities outward toward more ambiguous regions