Knight Hop

A knight starts somewhere on a five-by-five board and has to land on all twenty-five squares, once each, never returning to one it has already used. That is the knight's tour, cut down to a size you can finish in a few minutes — and cutting it down is what makes it sharp, because on a board this small most squares cannot begin a tour at all. This one only ever deals you a square a search has already proved a full tour exists from.

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 outlined.
2. Move the cursor with the arrow keys, or W A S D. The cursor is an outline, not a tint, so it is visible whatever your screen is doing.
3. Jump straight to a legal square with F. Press it again to cycle to the next one. A knight's move is three or four arrow presses away, and this skips the walk.
4. Hop with Enter or Space — or just click or tap the square. Only an unvisited square a knight's move away is accepted; anything else is ignored, so nothing is ever lost by trying.
5. Read the small numbers. Every square you can reach right now is marked with a diamond and the number of hops you would still have from there. Squares you have already used show the move number that landed on them, and the knight itself is marked ♞.
6. Do not paint yourself into a corner. If the knight has nowhere legal left to go while squares are still unvisited, the tour is over.

What is Warnsdorff's rule for a knight's tour?

Always hop to the square with the fewest onward moves. It was published by H. C. von Warnsdorf in 1823 and it is the reason a knight's tour is a puzzle you can reason about rather than one you have to brute-force. The intuition is that the squares with fewest exits are the ones about to become unreachable — a corner served by only two squares is stranded forever the moment both of those are used — so you spend them while you still can and leave the well-connected middle for later. Doing the opposite feels productive and is how almost every failed attempt ends: the knight cruises around the centre while the edges quietly close. This game prints the onward count on every square you can reach, so applying the rule is a decision rather than an arithmetic exercise. When two squares tie on the count, the rule is silent and the choice is genuinely yours — that is what the deal's "gentle", "steady" or "tricky" rating measures, and it comes from the solver's own run, not from a designer's guess.

Why can the knight only start on certain squares?

Because of a counting argument you can check in your head. A knight always lands on a square of the opposite colour to the one it left, and a five-by-five board has thirteen squares of the corner colour and only twelve of the other. A tour of twenty-five squares is twenty-four moves, so the colours alternate all the way and it uses thirteen of whatever colour it began on. Start on the twelve-square colour and you would need thirteen of them, which do not exist — so twelve of the twenty-five squares are impossible before you make a single move. Handing you one of those would be a puzzle you could not solve and could not know was unsolvable, so this game never deals one, and runs a depth-first search over the remaining thirteen to confirm a complete tour before dealing.

What happens if I get stuck?

The tour ends and it counts as a loss, with the squares you never reached marked ×. There is no undo: a knight's tour where you can take moves back is a different, much easier puzzle, and the whole lesson is in committing. The one thing you can be sure of is that the deal was not the problem — a full tour from your starting square was verified before you saw the board, so a dead end came from the route, and almost always from a hop that ignored a low onward count several moves earlier.

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

None, and there never will be. There is no currency, nothing to buy, no lives to refill and nothing to win or lose but the puzzle itself. The score is derived from your finished board, and it stays on your device.

Does it work offline?

Yes. After the page has loaded once, the board, the rules and the tour search all live on your device, and nothing is sent anywhere while you play. It is the same code with the network on or off.

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

Both. Arrows move the cursor, F jumps to the next legal square, Enter hops, and every square announces itself in words — "knight here, move 7", "visited, move 3", "legal hop, 2 onward options". Nothing depends on telling colours apart: the knight, a visited square, a legal destination and a missed square each carry their own glyph.

A five-by-five board and an open tour, so the last square does not have to be a knight's move from the first. One deal at a time, no undo and no timer. Warnsdorff's rule is a heuristic, not a guarantee: on this board it walks straight to a tour from ten of the thirteen valid starts and needs a rethink on the other three, and on much larger boards it is known to fail more often than that.

Peg Jump is the other board puzzle here where every move is irreversible and the skill is seeing the dead end before you reach it. Slide Fifteen is the opposite temperament — nothing in it can be ruined, so it rewards patience instead of caution.

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