COMBOS · LESSON 1 OF 3
4-Wide theory
AFTER THIS GUIDEYou can count residual cells and explain why a line clear must leave a useful next shape to continue the combo.
Every clear leaves the next puzzle.
A four-wide channel leaves four columns for successive clearing placements. The other six columns supply the filled part of each row. In a common three-residual setup, three occupied cells remain within the channel before the next piece.
Place a four-cell tetromino entirely into the channel and clear one full row through it: three existing channel cells plus four new cells minus four cleared channel cells leaves three. This count is the useful invariant. It assumes the piece stays inside the channel and exactly one row clears.
The count does not guarantee continuation. Three cells can form very different shapes, and the next piece may not fit. Read the arrangement after the clear and use NEXT and Hold to preserve a reachable next landing.
Combo means consecutive clearing placements. A placement without a line clear ends the chain under the trainer’s rules. Attack rewards for that chain vary by game; do not use a large combo number as a universal damage calculation.
Use the count, then inspect the shape
Locate the residual
In the channel diagram, separate the six-column stack from the four-column working area. Count only the occupied cells inside the working area.
Apply the one-row calculation
With three residual cells, a four-cell piece and one channel row removed, 3 + 4 − 4 = 3. If a piece crosses into the wall or you clear two rows, this simplified calculation no longer describes the same situation.
Plan the next piece
Imagine the residual after your proposed clear. Does the first NEXT piece have a clearing landing there? If not, compare a different orientation or Hold order before locking.
Three outlined cells remain inside this four-wide channel. Their arrangement matters for the next clear.
Top: one continuous combo. Bottom: the non-clearing piece ends the chain; the next Single starts again.
Common mistakes
Treating three cells as an automatic solution
The arrangement and the available piece matter. Count is a constraint, not a solver.
Building higher instead of learning continuations
A larger stack gives more potential clears, but it cannot repair a bad residual choice. Practise reading the channel before increasing height.
Picking the first Single you see
Compare the next residuals. One Single may preserve several routes while another leaves only an awkward dependency.
TAKE IT TO THE BOARD
Predict five residuals
- Open 4-Wide with Gravity Off and NEXT 5. The trainer uses the right-side channel.
- When clearing begins, pause before five placements and predict the channel cells that will survive.
- After each clear, compare the actual shape with your prediction. Use Undo to test one alternative when a chain stops.
What counts as progress? You can explain the next residual, not merely the line that disappears.
Open practice ↗Opens the mode. Set Gravity and NEXT yourself; your current settings are kept.
Keep these terms nearby
NEXT IN THIS PATH
Side versus centre
Compare the structures and the risks they create.
Read the next guide →Further reading
For setup variations and additional examples, see FOUR: 4-Wide. The practice task here is original to Stacking Lab.