Nonogram 20x20 is the largest size: 400 cells, up to eight runs per line and a long, steady solve. Like every grid here, it is verified solvable one line at a time. No app, no sign-up and nothing to click through before you start; it works offline, saves your progress and plays fully from the keyboard.
Nonogram board is loading.
A 20×20 needs nothing beyond line logic, but it punishes miscounting and rewards a system.
Go through all twenty rows, then all twenty columns, marking only what is certain. Start with the slack: 20 minus the runs minus the gaps. A clue whose slack is small, such as 6 4 6 with 18 cells needed and 2 to spare, fills most of its line at once.
Use the thick lines every five cells to count, and use the keyboard for precision: arrows move one cell, Home and End jump to a row's ends, and Page Up and Page Down to a column's ends. A miscounted run is the usual source of a mistake on this size.
On large grids crosses do half the work. Crossed cells split lines into sections, and short sections that cannot hold any run are empty in full. When a line is done, cross its remaining cells straight away.
Pause when you need to; the board hides and the timer stops. If you are stuck, the hint shows one cell with a one-line reason, which is usually enough to restart the sweep.
This page plays random 20×20 grids up to 680 px wide.
The timer starts on your first stroke and pauses when you switch tabs. Stats per size stay in this browser: played, won, win rate, best and average time. Undo and Redo cover every stroke. The first two hints on a puzzle are free; if ads are switched on later, more hints offer a short ad or a 30-second wait. Wins come with share text, and random puzzles have a code such as A7K3Q that replays them.
The 20×20 nonogram scrolls inside its frame on a phone rather than shrinking below 20 px cells, and a Scroll toggle keeps a drag from painting. Tidy Puzzles runs entirely in your browser: there is no app to install, no account to create and no interstitial before you can play. After the first visit the game also works offline, because each puzzle is generated on your device from a seed. Every board can be played with the keyboard alone, on a phone or a desktop, and your stats and unfinished puzzles stay in this browser rather than on a server.
Often an hour or more. Your progress is saved in this browser, so you can come back to it.
Up to eight. At most four rows and four columns are completely empty.
It uses the same logic but more of it, so the challenge is keeping track rather than new techniques.
Yes. Cells stay at least 20 px, the board scrolls inside its frame, and the Scroll toggle lets you pan with one finger.
No. Every grid is verified solvable by line logic before you see it.
Last updated 2026-09-27. Written and maintained by the Tidy Puzzles team; puzzles are generated on your device. How it works.