Block puzzle tips and tricks

A corner square has only two neighbours, so very few piece positions can cover it. Decide those squares early, while you still have every piece to choose from. Edges come next; the open middle can wait because almost anything fits there.

Fixed blocks, pegs and holes create new corners and narrow corridors. A one-square-wide corridor next to an obstacle can only take a straight piece or the end of an L, so fill it before those pieces are gone.

Long bars, pieces with thin arms and zig-zags fit in few places. If you leave them for last, the gaps that are left will almost never match. Small and compact pieces are your flexible reserve, so spend them late.

Every time a placement cuts the free space in two, you need the remaining pieces to fit both parts exactly. One connected region gives you far more options. Before you let go of a piece, check that it doesn’t wall off a pocket.

If a closed pocket has 3 squares and every piece left covers 4 or more, the level is already lost, however good the rest looks. In puzzles where all pieces are the same size (for example 4 squares each in the tetromino puzzle), every pocket must be a multiple of that size.

A single empty square with filled squares on all four sides can only take a one-square piece, and most block puzzles don’t have one. The same goes for a narrow dead end that is shorter than any piece left. If you create one, undo at once.

In our games the outline turns green where a piece fits. “Fits” is not the same as “good”: hover over two or three spots and imagine what is left around each one.

Colour the board like a chessboard in your head. A 2×2 square, a straight bar of four or an L of four always covers two light and two dark squares, but the T-shaped piece of four always covers three of one colour and one of the other. If the area you still have to fill has more of one colour, you know which kind of piece must go there.

Late in a level there is often a gap that only one remaining piece can fill. Place that piece first, even if it is not the one you were planning to use next.

Good players test ideas quickly and take them back. If you are unsure between two spots, try one, look at the leftovers, and undo if it looks worse.

When you take a hint, don’t rush on. Ask why that piece had to go there: was it a corner that only it could cover, or a pocket of the right size? That reason is the lesson.

Patterns you learn on a 4×4 box carry over to an 8×8 board. Short levels let you see more endings in less time, which is how you learn to spot dead ends early. The first levels of the tetromino puzzle and the kids’ puzzles are good for this.