Shikaku: Rectangular Divide — the puzzle of areas
Geometry instead of arithmetic
Among Japanese puzzles, Shikaku is the most "drafting-table" one: no mental arithmetic, just pure geometry. Numbers sit on the grid, and your task is to slice the whole sheet into rectangles so that every number lives in a rectangle of its own.
Three rules
1. One rectangle, one clue: no second digit may end up inside.
2. The area checks out: the number inside equals the rectangle's area, that is, the product of its sides.
3. No gaps, no overlaps: rectangles cover the entire board and never intersect.
How to think
A number is a list of options: "6" can be 1×6, 2×3, 3×2, or 6×1. Then geometry weeds the options out: a nearby clue can't be swallowed, the edge of the board limits stretching, a neighboring rectangle has already claimed the space. The possibilities shrink to one, and the board "clicks" into place.
In our version one click sets the first corner; clicking the opposite corner completes the rectangle. Made a mistake — click a finished rectangle to remove it.
Why it hooks you
Shikaku is puzzle-as-jigsaw: a chaos of numbers gradually assembles into a neat cutting pattern, and the last rectangle always lands with almost physical satisfaction. 8×8 is a warm-up, 11×11 is a full game. The generator slices the board fresh every round — no repeats — and the demo mode shows the model cutting.