Built to be closed, not returned to

The idea

Most puzzle sites are built to be returned to. They keep a streak for you, they hold a puzzle back until tomorrow, they ask for an account before you have played anything, and they interrupt a deduction with something flashing in the corner.

This one is built to be closed. Open a puzzle, play it for as long as it is enjoyable, and leave. Nothing expires, nothing is withheld until a particular hour, and nothing waits for you when you come back except your own best time.

Every puzzle here is a classic that has been around for decades — Sudoku, Minesweeper, nonograms, Sokoban, the fifteen puzzle, Hanoi. We have not invented a mechanic or bolted progression onto anything. What we have done is build careful versions of them, with generators that are honest about fairness, and write down how each one is actually solved.

Built light on purpose

Every page here is deliberately small, and that single decision is behind most of how the site feels. Nothing has to be assembled before you can start reading, nothing arrives late and shoves the text down the screen, and there is no advertising or tracking of our own anywhere on it. Our host adds a page-view counter on top of that, which the privacy policy describes.

This is not nostalgia. It is the reason a board is ready the moment the page appears, why nothing shifts under your finger while it settles, and why a page keeps working even when part of it never arrives. The quiet reveal animations sit on top of pages that already read perfectly without them, so anything that fails to load leaves you with plain text rather than a blank screen.

Puzzles that are actually fair

“Randomly generated” is doing a lot of work on most puzzle sites, and it often means a board that cannot be solved without guessing. We would rather do the extra work:

• Sudoku grids are built and then hollowed out one digit at a time. A digit is only removed if the grid still has exactly one solution, proved by counting solutions rather than assumed.
• The sliding puzzle is shuffled by making legal moves from the finished board, never by scrambling the tiles. Half of all tile arrangements are unreachable, and none of those will ever appear.
• Lights Out boards are produced by pressing a random set of cells on a dark board, then solved by the generator to confirm an answer exists and to work out the minimum number of presses.
• Crate Push levels are hand-built, and every one has been machine-checked to have at least one solution before it went on the site.
• Minesweeper never puts a mine under your first click, so no run is over before the board has told you anything.
• Where a puzzle needs randomness it comes from the browser's cryptographic random source, with biased values discarded rather than folded back in.

What we do not claim

We are not going to tell you that these puzzles make you smarter, sharpen your memory, or hold anything at bay. There is a large industry built on that promise and the evidence behind it is much thinner than the marketing. What we will say is that these are good puzzles and they are pleasant to think about, which seems like enough.

Every difficulty label and completion time quoted anywhere on this site is an estimate, taken from puzzles we solved ourselves. They are marked as estimates wherever they appear and they are not verified records.

The guides

A puzzle you cannot make progress on is not relaxing, it is irritating. So every puzzle has at least one guide explaining the actual reasoning — cross-hatching in Sudoku, the 1-2-1 pattern in Minesweeper, overlap in nonograms, chasing the lights, deadlocks in Sokoban.

There are twenty in total. Ten are the method guides for the ten puzzles, and the rest go further: intermediate Sudoku patterns, Minesweeper probability when there is nothing left to prove, the parity proof behind the sliding puzzle, opening theory for Connect Four, and a few on the puzzles themselves rather than on solving them.

They are written by the same people who wrote the generators, which means the explanations match the boards you will be given rather than a generic version of the puzzle. None of them are padded to hit a word count.

Read the guides, or open any puzzle and follow the link in its sidebar.

Getting in touch

If a puzzle misbehaves, a guide has a mistake in it, or something is unreadable on your device, we would genuinely like to know. The contact page has the details and a note on what to include.