The seven piece shapes and where they fit
The seven pieces, I, O, T, S, Z, J and L, one by one: what each shape is like and which surface it fits exactly without making a hole, with board diagrams.
A falling-block puzzle uses seven kinds of pieces, each made of four squares. Each one is named after the letter it looks like: I, O, T, S, Z, J and L. Every piece has its own “surface it fits exactly”, and once you know these, you can see at once where to put a piece without making a hole. This page looks at the seven pieces one by one: their shapes and where each one goes.
The seven pieces at a glance
| Piece | Orientations | Where it fits exactly |
|---|---|---|
| I | 2 | Four level cells (lying flat), a well (upright) |
| O | 1 | Two level cells |
| T | 4 | Three level cells, a one-cell dip, a one-row step |
| S | 2 | A one-row step (flat: higher on the right; upright: higher on the left) |
| Z | 2 | A one-row step (flat: higher on the left; upright: higher on the right) |
| J, L | 4 | Three level cells, two level cells, a gap two rows deep |
“Orientations” is the number of orientations that look different as you rotate the piece. The O does not change shape when you rotate it. After two rotations, the I, S and Z are back to their original shape.
I: the only piece that can fill a well
The I is four cells in a straight line. Lying flat, it fits on four level cells; standing upright, it goes into a well one cell wide. Only the I can fill a well three or more rows deep. “Stacking for Quads: leave one well open and clear with an I” explains a way of stacking that uses this: keeping one well open for the I.
O: only fits on two level cells
The O is a 2×2 square, and rotating it does not change its shape. That leaves it few places to go: the only place it sits without making a hole is on top of two level cells.
If you always keep two level cells free somewhere for the O, it will never leave you stuck.
T: the most places to go
The T is a piece with many places to go. It fits on three level cells pointing up, into a one-cell dip pointing down, and against a one-row step standing upright. It is the piece that helps you out when you are stuck, but once you learn T-spins, it becomes a key piece for scoring big.
S and Z: place them on steps
S and Z are the pieces that always make a hole on level ground. They fit one-row steps: a flat S goes on a step that is higher on the right, and a flat Z on a step that is higher on the left. Turn them upright and the direction of the step they fit is reversed.
On a flat board with no steps, S and Z have nowhere to go. “Flat stacking and managing steps” explains how to leave steps.
J and L: they can also fill a gap two rows deep
J and L are versatile pieces: by changing their orientation, you can place them on three level cells or on two. Turn them upright and they can also fill a gap two rows deep. As long as a gap is no more than two rows deep, you do not have to wait for an I.
Find a spot for the next piece in advance
Once you know where each piece goes, look at the first piece in the next preview before you place the current one, and find “where the next piece can go”. If you find it has nowhere to go, either change how you place the current piece to make room, or put it off with hold. “Look-ahead and elimination: reading the queue” explains this way of thinking.