Rectify: Shikaku Puzzles

Rectify is a Shikaku puzzle game with one rule and no end. Every number on the grid must sit inside a rectangle whose area matches it exactly, and every square must be covered. Learn it in thirty seconds; keep finding it interesting for months.

SIX GRIDS. LEVELS THAT NEVER RUN OUT.

Start on a 5x5 you can finish before the kettle boils, then work up through 6x6, 8x8, 10x10, 12x12 and 15x15. Each grid is its own endless ladder with its own level counter, so you always know where you are — and there is always a next level. Nothing is downloaded and nothing runs out: every board is generated on your device the moment you tap play, and every one is guaranteed to have exactly one solution.

TIMED TO THE MILLISECOND

Every solve is timed. Your best time on each grid is yours to beat, and the clock is what turns finishing a puzzle into getting good at one.

CHALLENGE A FRIEND WITH ONE LINK

Send anyone the board you just played and they get the identical puzzle — same clues, same solution — with your time to beat. No accounts, no sign-up, no server. The whole challenge travels inside the link, so it works even if they do not have the app yet: they install, and your board is waiting for them.

GENUINELY OFFLINE

Plane, underground, dead zone, no data left — it all works. Rectify has no backend at all. Nothing to sync, nothing to log in to, and nothing that stops working when the signal does.

FEATURES

- Six grid sizes, from a quick 5x5 to a demanding 15x15
- Endless levels on every grid, generated on device
- Every board has exactly one solution — no guessing, ever
- Millisecond timer with a personal best for each grid
- Send and receive challenges by link or QR code
- Daily streak, recent solves and personal records
- Light and dark themes
- Drag to draw, tap to remove — no menus in the way

HOW TO PLAY SHIKAKU

Drag across the grid to draw a rectangle. Its area — width times height — must equal the number inside it. Each rectangle holds exactly one number, rectangles never overlap, and the puzzle is solved when every cell on the board is covered. That is the entire rule set. The deductions it produces on a 15x15 are not simple at all.

If you like Sudoku, Nonograms, Picross, Kakuro, Killer Sudoku or any logic puzzle where careful deduction beats guessing, Shikaku will feel like home — and Rectify is the fastest way to play it.