The Long Way Round

One line. Every square. No square twice.

That is the whole rule, and it is the only rule you will be told. A small board appears with a marker sitting on one of its squares, and the line follows wherever you send it — arrow keys, or a finger dragged across the board, whichever suits you. Send it into a square you have already been through and it will not go, and it will say why.

The interesting part is that "visit everything" and "visit everything in an order that works" are not the same job. Almost any route covers most of the board. Getting the last square is what makes you think, because by then the line has already decided where it can and cannot go. Painting yourself into a corner is not a mistake to be embarrassed about here — it is the puzzle working. One press of Backspace takes a step back, as many times as you like, and nothing is ever lost by trying something and finding out.

There are five worlds and each one adds exactly one new idea:

1. Open ground — just the shape.
2. Walls — some squares are wall. The shape stops being a rectangle.
3. One way — some squares can only be left in one direction, so the ORDER you visit things in starts to matter as much as covering them.
4. Doorways — two squares far apart are linked, and you can step straight from one to the other.
5. Keys — a barred square will not open until you have been through the square holding its key, so now you have to reach one thing before another.

Each world holds twelve puzzles and opens the next one after eight, so a puzzle you happen to dislike never blocks the way. Every puzzle is built fresh, so coming back tomorrow does not mean doing the same boards again.

There is no clock anywhere in this. Nothing here is a test of how fast you can press a button. Take a whole afternoon over one board if you want to.

You can pick how the arcade looks — a bee over a honeycomb, a submarine over a reef, a cat over rooftops, or a comet across the night sky. The first one is free and yours to choose straight away. The rest arrive as you finish worlds, and none of them changes a single rule; they are only clothes.

What is remembered, and where

Which puzzles you have cleared, how many stars each one earned, which world and look you are on, and how many you have solved first time. All of that is written on your own device and none of it is sent anywhere — there is no account, no name, nothing about you at all, only which puzzles were solved. If your browser is set to block sites from storing anything, the arcade still plays in full; it simply will not remember, and it will tell you so rather than quietly forgetting.

Stars only ever go up. Going back to a puzzle you already cleared can improve what you scored on it and can never take anything away.

You need JavaScript for this one

The arcade is a game rather than a page, so it needs JavaScript switched on to play. With it switched off you get this description and nothing will pretend otherwise — there is no empty box below waiting for a line that cannot be drawn. Everything else on this site reads perfectly well without it.