Prism Blocks: make room for all three pieces

Plan three pieces on the 8×8 Prism Blocks board. Learn how row and column clears change the next move and why isolated gaps can end a run.

Look at all three pieces first

Prism Blocks lets you place ready-made shapes on empty cells of an 8×8 board. Drag a piece, or select it and tap its destination. Before placing the first shape, find a possible space for each of the three available pieces. If one fits in only a single area, another placement can block it. Check the whole order, remembering that a line clear will change the available space.

Use a clear to create the next space

A completely filled row or column disappears. One placement can complete both directions at once. For example, a row and column each missing their shared intersection may both clear when a suitable shape fills it, provided the shape's other cells also fit. Consider the shape of the remaining space as well as the number of empty cells. A broad open area is usually more flexible than scattered isolated holes.

Why a partly empty board can still end a run

The game ends when none of the remaining pieces can be placed. Empty cells alone do not guarantee another move: narrow gaps may fit no available shape. Avoid leaving a single hole while assuming the exact block you need will appear. Check the largest remaining piece again before placing. Pieces are positioned directly rather than falling from above, so falling-speed and falling-tetromino advice does not apply here.

Inspect the set before placing

1. Look at all three shapes and find at least one legal location for each in its current form.
2. Identify the piece with the fewest options. If it has only one place, check whether a smaller piece would occupy it.
3. Imagine the board after the first placement and any clear. Sometimes the cleared line creates the space needed by the next large piece.
4. Check the second and third steps. A convenient first placement alone is not a plan for the full set.
5. Recalculate after each actual move. Do not place automatically when a clear has changed the spaces you were using as reference points.

Example: a small piece consumes the only reserve

Suppose a large shape fits only in the broad empty area on the right. A small piece fits both there and in a gap on the left. Placing the small one on the right may remove the large piece's only option. Using the left gap preserves both moves. What matters is placing the available set, not the neatness of the first move.

There is an important alternative: the small piece on the right might complete a row that immediately opens the required area. Then that same placement can be correct. 'Always play the largest first' is therefore too crude. Account for complete rows and columns disappearing, then inspect the actual shape of the resulting space.

Count the shape of gaps, not just cells

Review an unsuccessful game

If a run ends with many empty cells, identify the remaining shape and exactly which area it lacked. Then recall the placement that split a larger opening into disconnected gaps. That is a more useful explanation than assuming the shapes were simply unlucky.

In the next attempt, preserve a flexible open area until a specific clear needs it. Do not leave single-cell holes assuming a matching piece must appear. You can predict the legality and consequences of the current three shapes; you cannot guarantee the next shape. Unlike falling-block games, this puzzle does not require importing advice about falling speed or tetromino rotation.

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• Prism Blocks