Preserve access to the next lower card.
This implementation uses nine Spades, Ace through 9, in three piles of three. Only a pile’s bottom card can move. It may go beneath a higher-ranked bottom card or into an empty pile. To win, build one column with 9 at the top, then 8 down to Ace at the bottom.
Last updated: September 2026
Read bottom cards and the cards above them
A bottom 4 can move beneath a bottom 7 because 4 is lower; a bottom 8 cannot. After moving the 4, the card directly above it becomes that source pile’s new bottom. Compare that reveal with the destination’s new bottom before choosing a move.
For example, if a bottom 4 covers a 3, moving that 4 beneath a 5 exposes the 3. The 3 can then move beneath the 4 if the 4 is still at the bottom of its destination pile. This makes a three-card 5–4–3 segment, ordered top to bottom.
Use an empty pile as temporary space
An empty pile accepts any bottom card and can expose a blocked rank, but the parked card occupies that space until it moves again. Before using the only empty pile, identify a legal destination for the parked card or a second move that will open another pile. A low card often has several higher-ranked destinations; a 9 needs an empty pile because nothing is higher.
Check the actual goal
There is one copy of each rank, all Spades. The win state is one nine-card pile in the visible order 9, 8, 7, 6, 5, 4, 3, 2, Ace from top to bottom. Clock is another compact card puzzle, but its move sequence is fixed by the deal; Tower of Pisa lets you select among legal bottom-card moves.