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Sliding tiles

Slide the numbered tiles into order, one into the gap at a time, within a par set by the exact fewest moves — 2×3 up to 3×4 boards.

  • Logic
  • Untimed
  • 36 levels

How it plays

The board holds numbered tiles and one gap. Each move slides a tile next to the gap into it; the move names the tile and the way it goes. Finish with the numbers in reading order and the gap in the bottom-right corner.

Every board was scrambled from solved by random slides, so it can always be undone. Par is the exact fewest slides, found by search, plus any slack you allow. Levels scramble deeper, and move from 2×3 through 2×4 and 3×3 (the 8-puzzle) to 3×4.

Keys

Space starts and skips ahead · 1–9 pick · Enter submits · Esc stops. On a phone, tap.

What it trains

This practises planning a few moves ahead under a constraint — what has to move out of the way first. It is practice at this puzzle and claims nothing wider.

Learn

How to get better at sliding tiles: the method, the techniques, what each new level asks of you, and the traps the wrong answers are made of.

Your approach to each question

  1. Find the tiles that are out of place, and how far each is from home. On a shallow scramble only a few are, and they sit along one short path of the gap.
  2. Note where the gap is. It must end in the bottom-right corner, so every slide should either bring a tile home or bring the gap towards the tile you are working on.
  3. On a deeper scramble, fix the top row first, in order, and do not disturb it again. On a board of three rows, then fix the second row the same way.
  4. Finish the last two rows a column at a time, from left to right, each column’s pair of tiles together.

Techniques and tricks

  • Count the distance first

    Add up how many cells each tile is from home, counting rows and columns. No solution can be shorter than that sum, so it tells you how close to par you can get.

    e.g. 1 2 3 / 4 _ 6 / 7 5 8: the 5 is one cell from home and the 8 is one, so at least 2 slides — and 5 ↑, 8 ← does it.

  • The parity check

    Each slide moves the gap one cell, so every solution is odd or even in length just as the gap’s distance from the bottom-right corner is. A detour therefore costs slides in pairs: one wasted slide is really two.

  • Turn a two-by-two

    With the gap in a 2×2 block, four slides take the gap once round the block and back, and move each of its three tiles one place round. Repeat it to cycle a tile into the corner you want without touching the rest of the board.

  • Finish a row in pairs

    The last two tiles of a row go in together. Put the second-last tile in the last one’s home and the last tile directly below it. Then bring the gap to the second-last tile’s home and slide the pair in: the second-last along, the last up.

    e.g. For a top row of 1 2 3: place 1, put 2 in the top-right corner and 3 below it. With the gap in the top middle, slide 2 left, then 3 up.

  • Go round the ring on two rows

    A 2×3 or 2×4 board is one loop of cells. Tiles only ever travel round that loop, so think of the board as a necklace and turn it until the order is right.

  • Never slide the same tile straight back

    Sliding the tile that just moved returns you to where you were, two slides poorer. If it feels forced, the slide before it was the mistake.

As the levels climb

  • You start on a 2×3 board scrambled by two random slides. Levels take turns: the board grows, then the scramble deepens by one slide.
  • The boards come in order — 2×3, 2×4, 3×3 (the classic 8-puzzle), 3×4 — up to the “Largest board” setting. After that only the scramble deepens, to 34 slides.
  • Shallow scrambles can be undone by eye: follow the gap back along the tiles that are out of place. On deeper scrambles the trail is lost; switch to row by row.
  • Par is the exact fewest slides plus “Extra slides allowed”. Row by row often costs more than the fewest, so as scrambles deepen you need the counting and the two-by-two turn to stay inside it.

Traps to avoid

  • Breaking a finished row: bringing a tile up through a row you have already fixed. Route the gap round below it, even if the way looks longer.
  • Placing the last tile of a row on its own: put it straight in and the row’s second-last tile gets trapped. Use the pair move instead.
  • Chasing a tile with the gap from the wrong side: the gap has to get in front of a tile to move it on. Bring the gap round to the side the tile is heading.
  • Reading the arrow as the gap’s move: “5 ↑” slides the 5 up into the gap, so the gap goes down.

How to practise

  • Set “Largest board” to 2×3 or 2×4 to learn the ring, then 3×3, then 3×4.
  • Start with “Extra slides allowed” at 4 or more to learn the methods, then bring it down to 0 so only the fewest counts.
  • Before your first slide, add up the distances and say the minimum. Check it against the fewest the working gives, after each board.

Levels

It is untimed unless you turn the clock on. There are 36 levels with the default settings, and the counter stops at the real top. Your level is judged on your last ten answers, every ten: 90% moves you up, below 80% moves you down, which holds most people near four in five right.

All of it is in the settings beside Start — how many answers a judgement looks at and how often it recalibrates, the thresholds, the time, which questions, how many options, and whether you see each verdict at once or review them together at the judgement. You can also jump to any level.

More logic

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