The Ivy Stack is a special game mechanic that introduces an additional challenge by temporarily restricting access to a column. At the start of the level, the column is covered with ivy, preventing you from seeing the blocks inside or moving them.
To unlock the Ivy Stack, you must fully complete one of the adjacent columns—either to the left or right. Once unlocked, the column may be empty or contain anywhere from a single block to a full stack, adding an element of unpredictability to the game.
This mechanic requires strategic planning, as you won’t know the contents of the Ivy Stack until you unlock it. Prioritizing the completion of an adjacent column can help reveal new sorting options and create space, making it easier to manage the remaining blocks and progress through the level.