Dead-end patterns
A field guide to the recurring shapes of a dying board — the speckle, the comb, the moat, the plateau, the canyon and the sealed corner — with how each forms and how to repair it.
Boards do not fail randomly. They fail in a small number of recognisable configurations, and once you can name them you start spotting them while they are still forming, which is the only time anything can be done.
What follows is a field guide. For each pattern: how it forms, what it still accepts, and whether it can be repaired. The two repair tools are always the same — a line clear driven through the affected area, or the full-board wipe once the energy meter fills — but knowing which pattern you are in tells you where to aim.
The speckle
Isolated single empty cells scattered across an otherwise dense board, each surrounded on all four sides by occupied cells.
How it forms: almost entirely from the concave sides of pieces. Every L, J, T, S, Z, corner triomino and plus has a bite out of its bounding box, and each time one lands next to existing material the bite can become a sealed void. No single instance feels costly. Twenty of them is the most common way a run ends.
What it still accepts: single cells, and nothing else. Every bar, every square, every notched piece is unplaceable in the speckled region. This is why a board can be a third empty and refuse almost everything.
Repair: a line clear straight through the densest speckled band, since a clear does not care what filled the line. Prevention is better: before placing a notched piece, check what its notch will leave behind, and orient it so the notch faces open space.
The comb
Alternating filled and empty columns, or alternating filled and empty rows — a striped board.
How it forms: usually from repeatedly placing vertical bars side by side with one column of clearance, or from a run of clears that took every other line. It looks tidy, which is what makes it dangerous. A striped board is orderly and completely useless.
What it still accepts: nothing wider than one cell. Vertical bars fit the empty columns. Single cells fit. Every square, every rectangle, every notched piece and every horizontal bar longer than one cell is dead, because nothing can span two adjacent empty columns when the column between them is filled.
Repair: complete one full row across the stripes. Every empty column is missing only one cell in that row, so a scattering of single-cell placements can do it, after which the row clears and the stripes are broken. Failing that, this is a textbook use for the board wipe. Prevention: place vertical bars flush against existing material rather than one column away.
The moat
A ring of filled cells with a hollow middle, or its inverse, an empty ring around a filled core.
How it forms: the filled ring comes from working outward from the edges without ever completing a line. The empty ring comes from the opposite instinct — filling the middle first and leaving a border one cell wide all the way around.
What it still accepts: the filled ring with a hollow centre is actually a healthy shape, provided the hollow is large enough to take the biggest piece. The dangerous version is the empty ring around a filled core, because a one-cell border accepts bars and nothing else, and the border cells belong to rows and columns that are each blocked by the core.
Repair: for the empty ring, drive a clear through the core. A row through the middle of the filled block splits it and connects the border to interior space. For the hollow-centre version, there is nothing to repair — just do not fill the hollow with small pieces out of habit. That is your nursery.
The plateau
Everything filled to a uniform level, so the boundary between occupied and empty is a straight line and the empty area is a clean rectangle a few rows deep.
How it forms: careful, even play. Players who consciously avoid holes often produce this, and it is far from the worst board you can have.
What it still accepts: anything that fits within the depth of the remaining strip. That is the catch — depth, not area. A plateau leaving three clear rows takes the three-by-three square and everything smaller. A plateau leaving two clear rows takes no three-by-three, no five-cell L corner, and no three-tall vertical bar, no matter how many empty cells remain. A two-row strip across the whole board is sixteen empty cells that cannot accept the largest piece in the game.
Repair: easy, and this is the good news. Complete one full row anywhere in the filled mass and the plateau gains a row of depth in the middle of the board rather than at the top. Because nothing settles after a clear, that freed row stays exactly where it was cleared, which is precisely what you want. Track depth, not emptiness.
The one-wide canyon
A vertical slot one or two cells wide, several rows deep, walled on both sides.
How it forms: two tall placements with a narrow gap between them, then material building up on both sides. It is the relative of the well that falling-block players keep open on purpose, except that here nothing falls into it, so it is not an asset.
What it still accepts: a one-wide canyon takes vertical bars and single cells. A two-wide canyon is much better — it takes two-by-two squares, two-by-three rectangles vertically, and both S and Z shapes — which is why the width of a slot matters far more than its depth.
Repair: complete a row that crosses the canyon. Prevention is simply never to leave a one-wide gap when a flush placement was available. Ask before each placement whether the gap you are leaving is one cell or two; the difference is enormous.
The sealed corner
A pocket of empty cells in a corner, cut off from the rest of the empty space by a wall of filled cells.
How it forms: placing a long bar or a rectangle across a corner region to get it out of the way. It is a fast, satisfying move and it quietly amputates part of the board.
What it still accepts: whatever fits inside the pocket. A sealed three-by-three corner is not a disaster. A sealed L-shaped pocket of five cells is nearly worthless, because the pieces that fit an irregular five-cell pocket are rare and you may never draw one.
Repair: complete the row or the column that forms the sealing wall. Corner pockets have an advantage here, since both the edge row and the edge column pass through the sealing wall, giving you two routes in. Prevention: before laying anything across a corner, look at what it cuts off, and prefer to run bars along an edge rather than across a corner mouth.
Reading the board for all six
A quick sweep, in this order, catches nearly everything while it can still be fixed:
- Count isolated single cells. More than two or three means the speckle is setting in.
- Look for stripes. Any alternating pattern of filled and empty lines is a comb forming.
- Check the depth of your largest open strip, not its area. Two rows deep will not take the biggest piece.
- Check every gap you are about to leave for width one versus width two.
- Look for empty space that has been cut into separate pockets, especially in corners.
- Ask the standing question: what is the largest piece this board would still accept anywhere?
If several of these are true at once, stop trying to play accurately and start planning a repair — a clear driven through the worst band, or the board wipe. Playing carefully on a board that is already in one of these states is just losing slowly.
Frequently asked questions
What is the most common way a board dies?
The speckle: isolated single empty cells scattered by the concave sides of L, T, S and Z pieces. It accumulates invisibly because each individual instance costs almost nothing, and the bill arrives all at once when a board that is a third empty stops accepting anything larger than a single cell.
Why is a striped board so bad when it looks tidy?
Because alternating filled and empty columns accept nothing wider than one cell. Every square, rectangle and horizontal bar becomes unplaceable, since no piece can span two adjacent empty columns with a filled one between them. Neatness and usability are different properties.
How much empty space do I need for the largest piece?
Nine cells arranged as a perfect three-by-three block, which means you need three rows of depth, not just nine free cells. A strip two rows deep across the whole board has sixteen empty cells and still cannot take it. Track depth and contiguity rather than count.
Can a dead-end board be recovered?
Sometimes. A line clear driven through the worst band removes nine cells of junk at once and often reconnects separated pockets, and the full-board wipe resets the geometry completely. What does not work is waiting for a better hand — the hand is drawn against your board, so the board is the thing that has to change.
Try it on a real board
Blockwood is a wood block puzzle on a nine-wide, twelve-tall board, with nothing falling and no dealt dead ends — every hand is checked against the board you actually have before it reaches you. Endless mode, timed mode, hand-built levels and a daily challenge. Free, offline, no ads and no account.