T-SPINS · LESSON 2 OF 6
Building your first TSD
AFTER THIS GUIDEYou can describe the four jobs in a basic TSD: cavity, overhang, completed rows and a reachable entry.
Build a route for the T, not a sealed T-shaped hole.
Start with a low, playable surface. Look for a place where a T would complete two rows. Those rows need all their other cells filled; a beautiful cavity with an unrelated gap elsewhere will not give a Double.
The overhang stops the T from falling straight into its final shape. That is why you need a rotation entry. The cavity must remain connected to open space above until the T has entered. A block added in the wrong place can preserve the final outline while making the route impossible.
Read the visible T before spending several pieces on a roof. If T is not imminent, use the intervening pieces on supported landings that preserve access. Hold can reorder available pieces; it does not supply an extra T.
A useful first goal is one shallow TSD followed by a clean stack. Repeating a flashy shape while leaving holes underneath teaches the wrong decision. The clear should make the next board easier to use.
Read the slot from the bottom upwards
Find the two rows
In the diagram, identify the two nearly complete rows. Ignore the roof for a moment: can you point to the exact missing cells the T will occupy?
Trace the entrance
The first frame shows a vertical T beneath the overhang. Its route remains open from above. Advance the example to see the final clockwise turn. Do not generalise this direction to a mirrored slot.
Predict the residue
Before clearing, mentally remove the two full rows. Then advance again and compare. The surviving blocks, not the disappearing T, determine your next placement.
The T is in position beneath the overhang.
One clockwise turn completes two rows.
T-spin Double: two lines cleared.
Common mistakes
Making the roof first
If the foundation still needs a piece underneath, roofing it can remove the drop route. Build low support before closing the shape.
Ignoring a gap on the far side
The T cannot clear a row that still has another empty cell. Scan across the entire width of both target rows.
Holding a T while the board becomes dangerous
If no reachable slot remains, use T as a stacking piece or take a smaller clear. Keeping a promise to an old setup is not worth losing access.
TAKE IT TO THE BOARD
One TSD, then five ordinary placements
- Choose TS practice, Gravity Off and NEXT 5. Keep Auto Play off while making decisions.
- Build one shallow TSD. Before the last roof placement, name the support, the entry and the next T.
- After clearing it, play five more pieces without forcing another spin. Repair the surface first.
- Repeat twice. When an entry fails, Undo the roof placement and test what access it removed.
What counts as progress? You complete a TSD and can still place the next five pieces without inventing a rescue dependency.
Open practice ↗Opens the mode. Set Gravity and NEXT yourself; your current settings are kept.
Keep these terms nearby
NEXT IN THIS PATH
TST and the magic key
Read a triple structure and the rotation that makes it work.
Read the next guide →Further reading
For setup variations and additional examples, see FOUR: T-spin rules and examples. The practice task here is original to Stacking Lab.