Read the tray before choosing a move

A tempting line clear can hide a practical problem: the next piece has nowhere to go. A short tray audit makes this easier to notice without claiming that one heuristic always wins.

Describe the shapes that remain

Before placing anything, list the occupied cells in each remaining shape. Keep the shape orientation fixed unless the particular game explicitly allows rotation. A vertical bar and a horizontal bar may contain the same number of cells, but they need different spaces.

Distinguish a shape from its rectangular envelope. An L-shaped piece can fit around an occupied cell that lies in the empty corner of its envelope. Conversely, an empty patch with enough total area may still fail because its cells are disconnected or arranged incorrectly.

Find legal anchors, not just open area

For each shape, imagine sliding its top-left anchor across the board. At each anchor, every occupied offset must land inside the board and on an empty cell. Mark anchors that satisfy both checks. This gives a set of legal placements for that shape in the current position.

For a small manual exercise, compare two candidate first moves from identical copies of the board. Apply the first move, perform the actual line-clear rule, and then repeat the anchor audit for the remaining tray. Do not reuse the anchor count from the board before the clear.

Interpret the count carefully

Zero anchors means the shape cannot be placed in that exact state. One anchor signals a narrow option, not necessarily a forced loss. Many anchors suggest flexibility, but the count alone says nothing about future pieces or scoring. Two shapes can compete for the same single opening, so separate positive counts do not establish that the whole tray can be placed in sequence.

A useful note records the input board, candidate move, cleared lines, and the remaining shapes with their legal anchors. Keep the coordinates so that someone else can reproduce the result.

Try the audit

The independent Blockblast.co project includes a Solver for examining positions with screenshot import or manual editing. Check the recognized cells and tray against the original image before comparing moves. Record the board first so the comparison can be repeated.

Disclosure: this guide introduces blockblast.co, an unofficial independent project not affiliated with Hungry Studio. It is a general geometry exercise, not a claim about a particular game’s hidden rules or a guarantee of a high score.