Cosmo Shikaku: Rectangles

Cosmo Shikaku is a rectangles puzzle: every number sets the exact size of a rectangle you draw on the grid. No tile swaps, no matching pairs - pure spatial logic, one clean rule.

WHAT SHIKAKU IS
Shikaku is a pencil-and-paper logic puzzle from Japan, a close cousin of Sudoku. The rule fits in one sentence: divide the grid into rectangles so each one contains exactly one number, and that number equals the rectangle's area in cells. Boards here range from a cozy 4x4 warm-up to big 8x11 grids, all generated fresh.

HOW TO PLAY
- Look at any number on the grid; it tells you how many cells its rectangle must cover.
- Drag out a shape of exactly that size - tall, wide, or square - around the number.
- Every cell belongs to exactly one piece, and every piece holds exactly one number.
- Keep going until the grid is fully covered. Each puzzle has one correct solution, so logic gets you there - never a guess.

A TRICK FOR BEGINNERS
Start with the biggest numbers and the ones tucked into corners - large shapes have far fewer ways to fit, so they lock in first. A lone 1 or a prime number like 7 or 11 can only form a couple of shapes, so hunt those down early too. Once the big shapes are locked in, look at what is left: a stray cell often has only one shape that can reach it, and that certainty is where the puzzle actually gets solved.

AN ENDLESS DIFFICULTY CURVE
Levels grow from a five-minute warm-up on a small grid to sprawling boards where reading the numbers is only half the job - later grids add stone obstacles, cells no shape can cover, so you plan around them instead of through them. Every layout is checked before it ships, so a stone obstacle only ever creates one fair path through the grid, never a dead end you cannot reason your way out of.

FAIR BY DESIGN
Every puzzle is generated with a unique, provable solution before you ever see it - no ambiguous grids, no lucky guesses. If a layout would need guessing to finish, the generator throws it out and builds another one instead.

DAILY PUZZLE AND STREAK
One fresh grid every day keeps a running streak alive. Miss a day, and Welcome Back rewards ease you back in instead of resetting everything you built.

FRONTIER
Every 10th level is a Frontier: a tougher board that pays double Stardust, and every 50th pays triple.

ALL ON YOUR OWN
Clear a board with three stars and without spending a single hint, and the game notices: going in all on your own pays extra Stardust.

HINTS ON YOUR TERMS
Stuck on a tricky grid? Spend a hint you have earned, or watch a short optional video for one more - it is always your call, never required to keep playing.

BOARD PALETTES
Unlock new pastel palettes for your board as you climb, including a seasonal palette every fifty levels - a fresh set of colors, not a repaint of the last one.

WELCOME BACK
Step away for a while and Cosmo Shikaku welcomes you back with a tuned reward instead of punishing the break, so your streak and progress are worth returning to.

PLAYS OFFLINE
No connection needed to sit down and solve. Cosmo Shikaku runs fully offline, on the couch or on a plane.

WHO IT IS FOR
If you like Sudoku, Nonograms, Kakuro, or logic puzzles in general, the rectangles here will feel instantly familiar and quietly addictive in their own way. Cosmo Shikaku plays well in short bursts or long sessions - open it for one grid on a commute, or chase the whole difficulty curve on a slow afternoon.

Open Cosmo Shikaku, trace one rectangle, and see how far your streak goes.