The puzzles differ; the app around them is the same. This page covers what every puzzle gets from it: hints that explain, checking your work, saving and checkpoints, and playing by touch, mouse or keyboard on any size of screen.
Simon Tatham’s manual for the original collection describes his desktop builds, and much of its common features chapter applies here too. Where the two disagree, this page describes the app you are using.
The first time you open a puzzle, its rules appear in a card over the board. Play closes it, as do Escape and a tap anywhere outside it, and Full rules and controls opens the puzzle’s whole page. The card is shown once for each puzzle and does not come back; the page is always in the Menu, as How to play.
Puzzles you solve by typing, such as Solo and Keen, show an on-screen keypad so they can be played by touch.
If you have a real keyboard and would rather have the screen space, turn the
keypad off in the
Many puzzles use both mouse buttons. When a puzzle’s help says “right-click” and you are playing by touch, you have four ways to do it:
Tap again. In many puzzles a click cycles a square through all of its states, so tapping again reaches what a right-click would, and then clears it.
Long press. Holding a finger down counts as a right-click. To right-drag, keep holding and move.
Two-finger tap. A second finger, anywhere on the screen, turns a touch into a right-click. The fingers need not land together: put the first where you want to click, then tap and release the second. To right-drag, lift the second finger and move the first.
The /
toggle. The Right click button at the end of the bar decides what a
plain tap means. Press it and it lights up: every tap is now a right-click,
until you press it again. It switches itself off when you leave the puzzle,
and a puzzle with nothing on the right button has no such button. You can
hide it in the
Tapping again is always available where a puzzle supports it. The others can be
tuned or turned off in the
In puzzles that have no use for a right-click, these gestures are switched off — Cube, Fifteen, Filling, Flip, Flood, Inertia, Pegs, Slide, Sokoban, Target and Untangle. There, holding your finger still simply presses; you can rest a finger on a peg while you decide where to jump it, and the drag still works when you move. A mouse’s right button does what the left one does.
Every puzzle uses two buttons and nothing else: a click or a tap is the left button, and a right-click or a long press is the right. Dragging works with either. So a puzzle plays the same whether you use a mouse, a trackpad or a touch screen, and nothing needs the middle button or a key held down while you click. Where a puzzle has more to do than two buttons can hold, there is a mode you turn on or a key on the on-screen keypad for it.
Many puzzles here have a Hint button, in the bar along the bottom of the screen (or down its side, in a window too short for that). It doesn’t simply reveal a move. It shows you the next move and explains why that move is forced, so that what you take away is a technique you can use again by yourself rather than one square you didn’t work out.
Every puzzle is meant to have one. A puzzle still waiting for its hint, or for another of the features on this page, is marked Draft on the home screen. It plays just the same; hold the pointer over the label to see what’s still to come. When a puzzle has no such thing by its nature, such as mistakes to check in a sliding-tile puzzle, its own help page says why under Not in this game.
Hint works in two beats:
Press once to see it. The board marks what the hint is talking about and the explanation appears just above the bar, without moving the board or any key. Nothing has been played — the move is still yours to make, with the puzzle’s own keys still in reach, and you’re free to make a different one.
Press again to play it. The button now says Apply the hint. A second press, with nothing done in between, plays that one step in slow motion and stops there. Ask again for the next.
Anything you do in between — a move of your own, undo, redo — puts the hint back to the first beat, so a second press always shows before it plays.
The words in pills point at the board. Tap or click one, “this cell” or “the outlined cells”, and the marks those words mean light up for a second, white on a dark board and black on a light one, while the rest stay as they are, and a line leads from the words to them. With a mouse, moving the pointer onto the words does the same. Each pill has a color of its own, and the marks it means are drawn in it: blues for what the hint decides, greens for what it reasons from, and warm colors for the line or region it names.
Auto-solve for me, in the Menu, plays hint after hint at about a second a step, waiting for each move’s animation in the puzzles that have one. Stop auto-solving stops it, and it stops by itself when the puzzle is solved or when the hint runs out of things to say.
A hint marks the board, and the marks mean the same things in every puzzle, so they’re worth learning once.
A ring, drawn around the contents of a square, is what the hint is acting on — the square, edge or line that the deduction forces. It is drawn around what’s there rather than over it, so anything you’ve already written stays readable underneath.
An outline around a row, region or area is the evidence — what the hint is reasoning from, as opposed to what it concludes. Where a puzzle’s evidence is squares that are empty by nature, this is a soft shade rather than an outline, since there’s nothing there to read through it.
Stripes across a row, column or region are the line the explanation names, when it says “this row” or “the striped region”.
Some puzzles need to point at two kinds of evidence at once — a filled square and an empty one, say — and mark them differently from each other. The explanation always names what it’s pointing at, so you never have to go by color alone.
In puzzles with pencil marks, you choose how a hint writes them, under Hints pencil in in the puzzle’s preferences:
Only as needed. A square with no marks counts as holding everything its row, column or region hasn’t ruled out yet, which is how many players solve before they write anything down. A hint writes a square’s marks only when its next deduction crosses one out or reasons from it, and tells you why those are the ones to write. Much of a sudoku then needs no marks at all. In Map, a region with no dots counts as any color its neighbors don’t show.
Every candidate first. The hint starts by filling in every square’s marks, as the button does, clears the ones the board already rules out, and reasons from the marks from then on.
Each puzzle starts on whichever suits it better: puzzles that mostly fall to squares with one possibility left, such as Solo and Seismic, start on the first; puzzles where nearly every square ends up needing marks, such as Keen and Towers, start on the second. The hints teach the same deductions either way.
Three quite different things stop a hint, and they call for different responses, so it’s worth knowing which one you’re looking at.
There’s a mistake on the board. A hint won’t reason from a position that already contradicts the clues, because everything it deduced from there would be wrong too. It refuses, and highlights the squares that clash — the same highlighting Checking your work uses. Fix those, then ask again.
Deduction has run out. Nothing further follows from what’s on the board. The puzzle is still solvable; there just isn’t a next step that can be explained, which is what an Unreasonable puzzle is for. Save your position, try something, and come back if it doesn’t work out — or take the answer from Show solution…, at the foot of the Help me play group.
The hint can’t see that far. In the two puzzles where a hint plans a route home rather than teaching a technique — Sixteen and Netslide — it works by searching ahead a limited number of moves. From a badly tangled position the way home is longer than it can search, and the honest answer is that it didn’t find one. This is not a claim that no move would help: play a few moves of your own and ask again, or take the answer from Show solution….
The hint says which of these has happened. It never guesses on your behalf and then presents the guess as a deduction: a guess that happens to come off is not a technique, and teaching you one would be the point. Guess, where guessing is the game, is the one place a hint suggests one — after pointing out everything the rows prove, and saying what it counted about the guess rather than claiming it is forced.
Not every puzzle has a Next hint button. A puzzle has one where it’s solved by reasoning and the game can put that reasoning into words. Where the challenge is dexterity, search or luck instead, there’s no technique to teach and no button to press.
Where a puzzle has a single provable answer, this app can tell you whether what you’ve entered so far contradicts it.
Check & save — on the bar of commands by the board, and on Ctrl/Cmd+S — checks the board and then saves your position if it’s sound. If it isn’t, it tells you how many squares are wrong, highlights them, and doesn’t save; the position you saved earlier is left exactly as it was, so a check you fail can never cost you the one you passed. Return to that saved position at any time with Back to last save, in the Menu beside the move number.
The check also asks the puzzle’s hint whether there is any way on from here. A position can be past saving without a single square being wrong: a peg in Pegs that nothing can reach again, a gem in Inertia the ball can never get back to, or entries that contradict each other with none of them provably wrong. When the hint would ask you to undo, the check says why in the hint’s own words, marks what it is about where it can, and doesn’t save, so your saved position is always one you can still finish from. In the puzzles whose hint works by searching ahead, a position can be further from the finish than the search can see. The check can’t settle that either way, so it saves, and tells you it couldn’t tell.
In a puzzle that can’t check itself the button reads the same and simply saves — one name for the save in every puzzle.
There is also a quieter Check without saving, low in the Help me play group. It runs the same check and reports it exactly as above but writes nothing, which is what you want when you already saved a position you mean to keep: the save slot holds one position per puzzle, so checking-and-saving would replace it.
Two things worth knowing about what the highlighting claims:
There is one saved position per puzzle. It’s separate from the numbered checkpoints in the history panel, which are a different feature: those live in your move history and you can hold several at once.
Many puzzles offer a range of difficulty levels in the type menu. Nearly all of those levels promise the same thing, and one of them promises something different.
On every level except one named Unreasonable, the puzzle can be finished by reasoning alone. You may not spot the next step, and it may be a hard step to spot, but there is always one there to be found, and you never need to try something out to see whether it works.
Unreasonable withdraws exactly that promise. Such a board may reach a position where no further step follows from what you can see, and the only way on is to pick one of the possibilities, play it out, and be ready to take it back. That’s not a flaw in the board; it’s what the name is telling you in advance. It’s also the only name that’s allowed to mean it — if a level is called something else, it doesn’t require this of you.
Three things make trying-and-taking-back cheap:
The hint knows about all this. On an Unreasonable board it will tell you when deduction has run out rather than making a choice for you and calling it a deduction.
Most boards are dealt at once. A large Custom type… size, or a rare combination of size and difficulty, can take many seconds to find. After a second the app says Looking for a board…, and the board you were on stays where it is: you can go on playing it, hints and all, until the new one arrives. When a page opens with no board yet, the commands that act on one (Hint, Check & save and the rest) are grayed out until it is there.
The search lasts two minutes at most, in every puzzle. If it finds nothing in that time the app says that no puzzle of the type was found, and you keep the board you have. Some combinations have no board at all, and some have boards so rare that two minutes is not always enough, and the app cannot tell which, so asking again is worth one more try.
Stop beside those words ends the search. You keep the board you have, and the type menu goes back to its type. Nothing is lost by stopping, and asking for the same type again starts a fresh search.
Once a board of a type has been found the app looks for the next one while you play, so the wait is mostly the first board’s.
Boards that aren’t square come taller than they are wide, to suit a phone held upright. When you start a new game on a screen that’s wider than it is tall, such as a desktop or a tablet on its side, a board that plays the same either way round is dealt turned, so it fills the space with bigger squares. The type menu still names the type you chose, and Custom type… shows the board’s size as it was dealt.
Turning your device never changes a game you’re in the middle of: the next new game fits the new shape. A few boards are always dealt the way you chose them, because turned they would be a different puzzle: Same Game and Bricks, where things fall downward; Slide, whose exit is always on the right; and the grid types in Loopy and Ascent that become a different grid on their side. Square boards, like every Latin square, are the same either way round.
In puzzles where you write small pencil marks into a square to keep track of what could go there, the button writes them for you: every square that has no marks yet gets everything that could still go in it. That gives you a full set to eliminate down from instead of a blank grid to fill in by hand.
It never undoes your own thinking. A square you have already narrowed by hand is left alone — the button only fills in squares that are empty of marks. And pressing it a second time doesn’t start over: in most of these puzzles it crosses out the candidates that the board has since ruled out, so repeated presses narrow rather than reset.
It is Fill marks (or Update marks once there are some to narrow), with the puzzle’s own controls beside its number keys. On a keyboard it is also the M key, on any board where M is not something you type: on a Solo grid of 22 numbers or a Group of 13 letters it is a value, and the button is the way to fill.
It’s a move like any other, so undoes it.
Many puzzles let you note what you are still working out — the numbers that could go in a square, or in Loopy the corners and pairs of edges you have worked something out about. Those notes go in through a notes mode, which is the same in every puzzle that has one:
While the mode is on, a small pencil shows on the board, so you can always see which kind of mark you are about to make. Notes are ordinary moves: undoes them, and they are saved with your position.
In some puzzles, placing a piece rules out squares at a glance: in Star Battle, no other star can touch a star. Those puzzles have a preference that marks them for you as you place, off until you turn it on. Its page in the help says what it marks.
One takes back the placement and the marks together, as one move, and that holds after you save and reload too. Taking the piece away later leaves the marks, since they may still be right.
A hint teaches the placement and leaves the marks to the preference: its next step is worked out from the board with them on it.
Some puzzles are about placing a known set of pieces, where the question you keep asking is which ones haven’t I placed yet. Those get a reference panel: a checklist of the whole set, marking off each piece you’ve placed and flagging any you’ve placed more than once.
Picking an item in the panel highlights where on the board it could still go. Closing the panel deliberately keeps that highlight, because on a small screen the natural order is to pick your piece, close the panel to see the board properly, and then place it. Press Esc, or pick the same item again, to clear it.
In a puzzle where you are building up one continuous path, the question you keep asking is which of these pieces are already joined together — and once the board has a dozen fragments on it, the honest answer is that you trace them with your eye.
Where a puzzle can answer that, resting the mouse pointer on part of what you have drawn lights up everything connected to it. Loopy does this: hover any line and the whole run of lines it belongs to is highlighted, so you can see at a glance whether the two ends you are about to join are already the same piece — which, in Loopy, is the difference between finishing the loop and closing a small one by mistake.
Nothing depends on it: it shows you something the board already contains, faster than tracing. It is a mouse feature, since a touch screen has no notion of hovering — a finger is either pressing or absent — so on a phone or tablet you will not see it.
Undo reaches past the two commands that put your work away. Each gives you a fresh board, and the move counter counts from it: after Start over or a New game you are at move 0.
Start over puts your moves away, and Undo brings them back. It returns the board to how it started, and the timer to zero. Undo straight afterwards and your moves are back, where you left them, with the time they took; redo starts over again. Starting over on a board you have played nothing on does nothing. (In Mines the board “as it started” is the one just after your first square opened, so you needn’t remember where you began.)
The boards you left are kept behind the new one. When a new board replaces the one you were on, whether by New game, a choice in the type menu, a shared game or a loaded one, the old board waits behind the new one’s first position. Undo there, with no move of the new board left to take back, brings the old one back as you left it: its moves, its checkpoints and its time. Redo, from the old board’s last move, returns you to the new board.
So Undo walks back through everything you did this session: your moves, your Start overs and the boards before this one, up to a hundred boards back. Making a move lets go of what Redo would have returned to, as it always does. The history panel offers the step either side of the board in play as Previous board and Next board, or Before starting over and Started over. Closing or reloading the app lets go of the other boards; your Start overs on the board in play are kept with it.
A checkpoint marks a position in your move history so you can come back to it: a shortcut for a long run of Undo. They earn their keep on an Unreasonable board, where you may have to try a line and take it back.
You can hold several checkpoints at once. If you want a single position to return to, and the board checked before it is kept, that is the separate saved position.
To set one, open the history panel (beside undo and redo) and choose Save checkpoint, then carry on. If the line doesn’t work out, pick the checkpoint in the panel to rewind to it.
Back at a checkpoint, undo and redo still walk the history around it. Your first new move, though, discards everything after that point, later checkpoints included; if you change your mind before making one, Last move in the panel redoes all the way to the end. A checkpoint you no longer want goes with its delete button.
Checkpoints are experimental and may change shape.
Every puzzle times you, with a clock beside the move count. If you
would rather not see it, turn off Show timer in that puzzle’s
The clock starts with your first move, not when the board is dealt, and it stops while the app is out of sight. Once you have solved the board, the time is final: undoing afterwards will not restart it. If you lose (in Mines, say), the clock waits while the board stays lost and carries on if you undo. Starting over sets the clock back to zero, as it does the board, and the help the app gave goes with it; undoing the Start over brings both back with your moves.
When you solve the board, the time appears in the message that congratulates you. If the app helped on that board, the message says so beside the time. A hint counts as help, and so does the solver, and so does a check that found something: a mistake, or a position there is no way on from. A check that finds nothing wrong does not count, so saving a sound board is always free.
Each puzzle keeps your game in progress and resumes it when you come back, whether you closed the tab, wandered off, or hit a bug. Starting a new game, or choosing another variation or difficulty in the type menu, replaces it, and undo brings the old game back.
On the home screen, a puzzle with a game in progress wears a triangle on its icon.
To discard every game in progress, open the
Share in the Menu (or
This specific game: a link to the game you are playing, as it was dealt. The link carries the board itself, so it opens the same game after the app is updated. It doesn’t carry your progress; for that, export a save file or copy as text. Opening a link to a board you are already playing on this device picks up where you left off.
This puzzle type: a link to the current type, meaning the size, difficulty and any other options. Opening it deals a new random game of that type, which makes it the way to pass on a custom type.
Copy as text: the board as plain characters, for pasting into a forum post or a message. Use a fixed-width font (“format as code”). Not every puzzle can do this, and some of the renderings take a little imagination.
Game ID: the game itself, without the link around it, for any compatible app. Simon Tatham’s manual explains the format under Specifying games with the game ID. This app shares no random seeds: a seed only tells a generator what to deal, and some puzzles here generate differently from the original, and from earlier versions of this app.
To open a game someone sent you, open its link, or paste the link into
For puzzles that exist on Simon Tatham’s website, the share dialog also links the same game there, by its game ID, which is handy for comparing behavior when something looks wrong.
Save as… in the Menu keeps the whole game, undo history and checkpoints included, and Open saved… brings it back. Saved games stay on your device, in your browser’s storage.
Export… in the save dialog writes a file you can move to another app that plays the collection, or attach to a bug report; Import… in the load dialog reads one in. (Exported files leave checkpoints behind for now.)
To delete every saved game, open the
Your games and settings stay in your own browser, on your device. The