NovaCove Labs

Picture logic

Piqora

A grid guarded by rows and columns of numbers. From those numbers alone you work out which squares are filled and which stay empty, until a hidden picture comes out of the emptiness.

The rule of the house

No luck. No guessing. Every board is built so reasoning alone gets you there, which is why a finished grid is something you earned rather than stumbled into.

Creatures
Objects
Symbols

Tools, not crutches

Tap to fill, cross off the squares you've proved empty.
Undo and redo, for testing a line of logic without fear.
Finished rows and columns dim their own clues.
A limited supply of hints reveals one deducible square.
Strict mode counts mistakes, for people who want that.
Every board auto-saves the second you step away.

From warm-up to long haul

Dozens of hand-checked puzzles in themed packs, from gentle five-by-five starters to twenty-by-twenty grids, across easy, medium and hard. Watch a pack's progress ring fill, chase better times on boards you've already cracked, and finish to a flourish as the picture reveals itself.

5×5warm-ups

20×20the long ones

3difficulty tiers

Working out

Why every puzzle has to be checked by hand

Clues describe a picture, but they don't always describe only one. Draw anything in this four-by-four grid: the page reads off its clues, then tests all 65 536 possible four-by-four pictures to see whether any other picture would produce exactly the same numbers.

Only one picture fits

Counted exhaustively over every four-by-four picture: 58 196 different clue sets exist, 52 362 pictures are pinned down by theirs, and the rest share. That's four in five safe, one in five ambiguous. The worst clue set in the whole space is shared by 24 different pictures.

The pattern holds as grids grow: at three-by-three exactly 75% of pictures are uniquely determined, and a sample of 60 000 random five-by-five pictures came out at about 75.5%. A puzzle pack is the rare fifth that got checked.

Grid size 20 × 20

2.58 × 10¹²⁰ pictures

More than every atom in the observable universe, which is somewhere near 10⁸⁰.

What's not here: nothing to solve. This runs the puzzle backwards — you give the picture, it reads the clues — and at four-by-four it's a toy. There are no boards, no clue-solving, no hints and no packs on this page. Those are the app.

Get it

Offline, no account, no ads. Pick an accent theme, set your default fill mode, and solve anywhere.

Piqora on Google Play Package com.gridkindle.piqora

On paper

Company: ELECTRICITY CREW & CLT PTY LTD, trading as NovaCove Labs
Director: Michelle Connell
Address: 80 Renou St, East Cannington WA 6107, Australia
Email: solve@electricitycrew.rest

Found a board with two answers, or a clue that dims when it shouldn't? Send the pack and the puzzle number: an ambiguous puzzle is a bug and we pull it.