Gravity row-clear puzzle

Place falling four-cell pieces, clear completed rows and preserve the remaining board state.

Shape & spatial thinking · Logic & rule checking

Players

1–2 cooperative players

Time

12–18 minutes

Materials and quantities

One 6×8 grid, ten-piece shape queue, pencil, eraser and a row-clear log.

One shared board per pair; preserve the queue order for comparisons.

Prepare

Use a six-column board A–F, rows 1–8 from bottom to top. The fixed queue is I, O, T, L, I, O, T, L, I, O. Each piece has four edge-connected cells, shown on the shape sheet. Before each drop, choose a rotation and horizontal position. Reflections are not allowed. There are no sideways moves after descent begins; this paper version is a discrete puzzle, not a realtime falling-block application.

Play

Lower the entire chosen piece vertically until another step would hit an occupied square or go below row 1. All four cells must then lie inside the board; if part remains above row 8, the attempt ends. Mark its cells. Remove every now-full six-cell row simultaneously. Shift each surviving cell down by the number of removed rows below it. A gap in a row is not removed, and a partly full row is never compressed sideways.

Worked example

Drop a horizontal I into A1–D1. Drop an O into E1, F1, E2 and F2. Row 1 becomes full and is removed. The O’s upper cells descend from E2/F2 to E1/F1. The board now has exactly two occupied cells, not an O floating above an empty row. The first two queue pieces can make this state; no alternative shape or hidden initial block is required.

Finish and check

Score one point for each removed row. Finish after ten pieces or immediately when a piece cannot fit after its legal descent. Record pieces used, cleared rows and the final board; compare two attempts only with the same queue and rules. There is no claim that the example is an optimal score. Do not erase a wrong placement silently: preserve it in the log and restart that attempt if the state cannot be recovered.

Adaptation and practical limits

For a first attempt, trace each rotation on spare paper before committing. One partner chooses placement and the other checks the drop and row shift, then swap. Use a pencil and large hand-drawn squares if printing is unavailable. An adult may do cutting if using movable four-cell templates; the game can also be completed entirely by drawing, with no small loose components.

Free alternatives: Use paper or clean reused cardboard and a pencil. Copy the supplied diagrams and tables by hand; no specialist kit or purchase is needed.

Printable materials

Preview at 100% scale, with browser headers and footers off. Cut with suitable help. Keep host keys separate. This is a manual tabletop kit, not an online opponent, automatic judge or solver.