Upstacking
Upstack refers to the pieces dropped onto the playfield. Upstacking refers to "stacking up" pieces to score larger line clears, usually on the bottommost rows of the stack. Aim to keep the stack open to multiple placement choices, since you won't always get the right piece. Pieces not fitting result in holes and gaps. When you can't clear lines because of the holes, you must stack even higher. This ultimately leads to topping out. Build surfaces that will maintain good spots for any piece, and even any next piece after receiving any piece. Note: I have ignored holding and soft dropping for this article. Their use can make some ideas difficult to explain. Contents The Basics Good and bad surfaces Creating options for S- and Z-pieces Smoothing things out Prioritizing lower placements The jagged corner Surface connectivity Piece-specific planning S- and Z-pieces O-pieces I-pieces T-pieces Parity