Mirror Maze

A beam leaves the emitter on the edge of the board and travels in a straight line until it meets a mirror set at 45°, which turns it through exactly 90°. Some mirrors came with the board and cannot be moved. The rest are in your hand — and you get exactly as many as the puzzle needs, never one spare, because that number is what the solver proved is the minimum. Place them so the beam ends up on the detector. The whole path is drawn as you work, so you can see precisely where your route stops agreeing with the target.

It runs entirely on your device: 0 network requests, works offline. No ads, no account, nothing to buy, and no betting, money or prizes of any kind.

1. Focus the board — click it, or press Tab until it is focused.
2. Move the cursor with the arrow keys, or W A S D.
3. Press Enter or Space to cycle the square under the cursor: empty becomes ╱, ╱ becomes ╲, and ╲ becomes empty again — which puts that mirror back in your hand. Or just click any square to do the same thing there.
4. Press Backspace (or Escape) to lift a mirror straight back to your hand without cycling through ╲ first.
5. Watch the three numbers. In hand is how many mirrors you have left, Moves is your budget, and Still needed is the fewest further mirrors that could finish the board from where it stands right now. If Still needed reads "not with these", the arrangement on the board can no longer be completed with what you are holding — lift one and try somewhere else.
6. Light the detector. The beam has to arrive on the ◎ square; passing near it does nothing.

Every press that changes the board costs one move — placing, turning and lifting alike. Presses that cannot do anything are free: a fixed mirror, the emitter, the detector, or an empty square when your hand is empty. Nothing is ever taken from you for pressing the wrong square.

How do you solve a puzzle where you place mirrors to steer a beam onto a target?

Work backwards from the detector, not forwards from the emitter. Ask one question: which square must the beam be on, and travelling which way, one step before it arrives? On a grid there are only ever three answers — coming along the row from the left, along the row from the right, or down or up the column — and the fixed mirrors usually rule out two of them straight away. That gives you a short line of squares the beam has to be travelling along. Now ask the same question of that line: what could put the beam on it, heading that way? Two or three links of that chain and you have met the emitter's own beam, which is already drawn on the board for you. Forwards, you are guessing among dozens of squares; backwards, you are choosing between two or three at every step. The other half of the trick is remembering the rule exactly: ╱ turns a beam travelling right into one travelling up, and ╲ turns it down — and because reflection is symmetric, the same mirror turns a beam travelling down into one travelling left, and so on around.

Is every board actually solvable?

Yes, and by construction rather than by luck. The generator builds a working route first: it walks a beam out from the emitter, dropping a mirror wherever it wants the beam to turn, and the square the walk finishes on becomes the detector. Only then does it lift some of those mirrors back off for you to restore, so a complete solution demonstrably existed before the puzzle did. The extra mirrors scattered around the board are only ever placed on squares that route never touches, so they cannot break it either.

Why am I never given a spare mirror?

Because a solver measured how many the board needs, and that measurement is what you are handed. After the board is dealt, a search runs over the beam itself and finds the smallest number of mirrors that can reach the detector — placing one, following where the beam then goes, placing the next, and so on, deepening from zero upward so the first depth that works is by definition the minimum. Your move budget is that number times four, plus four. So the target is always reachable and always tight: there is nothing spare to brute-force with, and every mirror you hold has to earn its square.

Is there any money, betting or in-app purchase in this?

None, and there never will be. No currency, nothing to buy, no lives or hints for sale, no prizes, and no gambling of any kind anywhere in Demystify Play.

Do I need to see colour to play this?

No. Every square draws what it is: a triangle for the emitter and the way it fires, a diagonal for each mirror and the way it slants, a box-drawing line for the beam and the way it runs, and a ring for the detector — hollow while it is dark, filled once it is lit. Your own mirrors have a dashed edge and the corner word "yours"; the board's have a solid edge and the word "fixed". Turn the screen greyscale, or print the page, and nothing at all is lost.

Can I play it with a keyboard or a screen reader?

Both. Arrow keys or W A S D move the cursor, Enter or Space cycles a square, Backspace lifts a mirror, and every square is a real button you can reach with Tab. The live region names each square in words — which mirror is on it, which way it turns the beam, whether the beam is passing through — and after every move it says where the beam now leaves the board, how many mirrors you hold and how many more would finish it.

Does it work offline?

Yes. Once the page has loaded once, the whole game is on your device — boards are generated in your browser from a seed, so there is no level server to be offline from.

Seven squares by seven. Boards are dealt until the solver says at least three mirrors are needed, so one-bend puzzles are redrawn rather than served. The beam is absorbed by the detector and by the emitter's own housing, and it cannot loop: every reflection is reversible, so a repeated position would need two different squares to have led to it. There is no undo of a whole move — lifting a mirror is itself a move, which is what makes each placement a decision rather than a trial.

Tilt Maze is the other spatial puzzle here where you cannot stop midway and have to choose what will stop you, and Pipe Flow shares the business of joining a source to a drain one tile at a time.

Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.