About this notebook

GridPencil is a small website with one idea behind it: a good puzzle needs very little. A grid, a rule or two and a clear finish are enough to hold someone's attention for five minutes and leave them feeling slightly cleverer.

What is here

There are twenty puzzles, grouped into five kinds: logic, numbers, paths and moves, colour, and memory. Each has its own page with the rules, an estimate of how long it takes and a guide to solving it. We wrote those guides ourselves, and they describe how these particular versions behave, not puzzles in general.

How the puzzles are made

Each puzzle is a small program that runs in your browser. Most of them create a new board every time you press "New puzzle", so you will not run out. Where a random board might turn out to be impossible, the program tests it first and only shows you ones that work.

We have tried to make them comfortable to use. Every puzzle can be played with a finger or a mouse. Colours are always paired with a number, letter or shape. The page follows your device's light or dark setting, and the button at the top switches it.

What it costs

Nothing. The site is free and needs no registration. To cover its costs it may show advertising, which is placed between sections of a page and never over a puzzle. Our privacy page explains what that involves.

What we do not do

We do not ask for your name or email address. We do not keep scores or progress on our server. We do not offer downloads, and nothing on the site should ever ask you to install anything.

Say hello

If a puzzle misbehaves, if you find a mistake in a guide, or if there is a puzzle you think belongs here, write to hello@example.com. The contact page lists what is useful to include.