A tower is not a turtle with extra height, and the tactics that finish a flat layout will strand you on a tall one. The difference is where legal moves come from. On a tall board almost every free tile is the top of a column, and almost every locked tile is in the slab those columns stand on. Height is cheap: it peels away one tile at a time and supplies a steady stream of partners. Width is expensive: a row of tiles standing shoulder to shoulder opens only from its two ends. Play a tall board as two separate resources and the finish rate changes.
The crown gives, the slab takes
Read a tall layout as two structures. The crown is everything above the base: spires, ridges, stepped ledges, single columns, each of them offering one liftable tile at a time. The slab is the flat foundation, usually a rectangle several tiles wide, where interior tiles have neighbours to left and right and nothing above them that could be removed. No amount of clearing overhead frees an interior slab tile. The only thing that does is the shortening of its row from one of the ends.
So the crown is your supply of matching partners and the slab is the bill. Spend the crown on itself, crown tile matched against crown tile over and over because those matches are always there, and you arrive at the slab with a wide flat rectangle, two open ends per row, and nothing left to match them against.
Match one crown tile with one slab end
That is the whole discipline, and it works better as a preference than a rule. Given a choice between a match that uses two crown tiles and one that uses a crown tile plus the end of a slab row, take the second. It costs a single unit of supply and buys a unit of progress on the part of the board that cannot progress by itself. The first option costs the same unit of supply and buys nothing except a slightly shorter column.
Count what each spire is standing on
Every column is a debt written against the tile underneath it. A spire five tiles high means five removals before the slab tile below is even a candidate, and those five removals need five partners. Before committing to a plan, walk the crown and count: how tall is each column, and how many pairs will the crown supply in total. If the arithmetic says the crown runs out before the tallest spire is down, start spending crown matches on slab ends now, while the partners to do it still exist.
Work the slab from both ends
Rows open at their ends, so a slab row of eight tiles is a queue with two heads. Take from both rather than eating one row from a single side: worked from one end a row offers one candidate at a time, worked from both it offers two, and two candidates are two chances that one of them matches something in the crown. Note also that a row in the middle of the rectangle is no harder than one on the outside. The freeing rule looks at left and right neighbours only, so a tile in the top row of a flat rectangle is exactly as stuck as one in the fourth row down. This is where players arriving from flat connect grids misread the board, because there the outer ring genuinely is easier. The site’s own example of it is Microsoft Mahjong.
Single columns and the tiles that hide under them
A column one tile wide is the friendliest structure on a tall board: its top tile is free by definition, since nothing sits above it and nothing stands beside it. That also makes it the easiest thing to over-harvest. Columns hand out tiles with no resistance at all, so they are usually where a crown gets spent without anyone noticing. Take from a column when its top tile pairs with something on the slab, and leave it standing when it does not.
The second thing about columns is what they conceal. In a deep stack an identical tile can end up directly beneath its twin, and inside a column that is invisible from above, so you count three copies of a design where there are four. A twin sitting under its own copy kills that design and everything below it.
When a shuffle earns its cost on a tall board
Tall layouts are the case where a shuffle is most tempting and least reliable. Tempting, because a stalled tower usually still carries a large number of tiles and looks recoverable. Unreliable, because a shuffle redeals faces into the same slots and a tower’s problem is structural: a slab locked shoulder to shoulder does not unlock because the pictures moved. Spend the shuffle while the crown still has several columns standing, since that is where a redeal genuinely changes which pairs are reachable. Once the crown is gone and only the slab remains, it rarely buys more than a move or two. Coffee Mahjong is one of the layouts kept on this site.
Boards to try this on
Any tall layout serves. The tower layouts collect the ones built on the crown-and-slab pattern, and Mahjong Tower is a straightforward example on which to count columns before starting. The general removal order this sits inside is in the solitaire order of play, and the split between layout puzzles and the table game in the strategy pillar. A layout of that kind in the catalogue here is Super Mario Mahjong.
