Count before you drop
3-minute read
The pieces in a Fill the Space tray always add up to the room. That sounds like a fact about the start of a room, but it’s really a tool for the middle. At every moment, the empty cells must be filled exactly by the pieces still in the tray. When a drop breaks that, the room is lost, even if it still looks wide open. A few seconds of counting catches it before you let go.
The one-cell pocket
The simplest failure is a single cell you can’t reach. Here’s the warm-up room from Fill the Space #2 (September 24, 2026) with its T dropped flat in the bottom-left, bump down.
The corner under the T is now a pocket of one cell. The smallest piece left in the tray holds three. No arrangement of the remaining pieces will ever fill that cell, so every drop after this one is wasted. You’d have to move the T, and moving a piece already in the room counts as an extra drop.
Pockets of one or two cells are easy to spot once you look for them. The habit is to look every time, at the cells around the spot where the piece will land, before you let go.
Islands that don’t add up
The sneakier failure leaves no tiny pocket at all. Take the warm-up room from Fill the Space #6 (September 28, 2026). Its tray holds a big V of five cells, a P-shape of five, and two straight threes, one lying down and one standing up.
Drop the V with its corner low and its arm reaching up the middle, and the room splits in two: a square of four cells in the top-left, and a seven-cell L along the bottom and right edges.
Both islands look roomy. Neither can be filled. The pieces left hold 5, 3 and 3 cells. No mix of them makes 4, and no mix makes 7 either: 3 + 3 is 6, 5 + 3 is 8. The room was over the moment the V landed there.
The fix is a quick sum whenever a drop would cut the empty space into separate islands. Count each island’s cells, then ask whether the tray’s pieces can be shared out to match. You don’t need every combination, just one that works. If there isn’t one, try somewhere else.
Why counting beats trying
You could find all of this out by dragging pieces around. But in Fill the Space every drop counts. A room is Perfect only when each piece is placed once. Each extra drop knocks 10% off the room’s points, and ten extra drops end the room. Counting is free.
It also gets easier as the room fills. Early on, the islands are big and almost any total works. Late in a room, with two or three pieces left, the sums are small and the answer is obvious once you think to ask the question.
A quick routine
- Pick up a piece and hover it over where you want it.
- Look at the cells around it. Is any cell left alone, or in a pair?
- Does the drop split the empty space? If so, count each island.
- Check the tray: can the pieces left be shared out to match those counts?
- If yes, drop it. If no, lift it away before you let go and look again.
Counting tells you where a piece can’t go. To find where it must go, start with the corners and dead ends.
Next guide: Pieces don’t turn